how can i separate the mainDomain and the subDomains use mod-rewrite with htaccess file - .htaccess

Question

I want to redirect subdomains on my site if they are queried, but if I do not query, I want to redirect it to a different domain.
I have reached some codes by searching the internet, but I have not improved.
If I can not tell what I want to do, I want the following url and file structure to be the same as I showed.
public_html/
|____.htaccess (main htaccess)
|____index.php (php empty)
|____mainDomain/
| |_____.htaccess (without subdomain htaccess)
| |_____index.php
| |_____public/
| | |____.htaccess (application htaccess)
| | |____index.php
|____subsDomain/
| |_____ucgen/
| |_____testFolder/
main htaccess:
RewriteCond %{ENV:REDIRECT_SUBDOMAIN} =""
RewriteCond %{HTTP_HOST} ^([a-z0-9][-a-z0-9]+)\.metehanboy\.com\.?(:80)?$ [NC]
RewriteCond %{DOCUMENT_ROOT}/subsDomain/%1 -d
RewriteRule ^(.*) subsDomain/%1/$1 [E=SUBDOMAIN:%1,L]
RewriteRule ^ - [E=SUBDOMAIN:%{ENV:REDIRECT_SUBDOMAIN},L]
RewriteRule ^$ mainDomain/ [L]
RewriteRule (.*) mainDomain/$1 [QSA,L]
without subdomain htaccess
RewriteEngine on
RewriteRule ^$ public/ [QSA,L]
RewriteRule (.*) public/$1 [QSA,L]
application htaccess
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?hedef=$1 [PT,L]
I added cpanelden subdomains but infiniteloop happens when I run the subdomain, how can I fix this?
example subdomain link: http://ucgen.metehanboy.com/example/example
other link: http://metehanboy.com/authentication/index
mainDomain folder include mvc php app
subsDomain folder includes test application scripts
Apache Error Log
[Wed May 02 14:16:26.044185 2018] [core:alert] [pid 3117] [client 95.70.153.106:59513] /home/metehanboy/public_html/.htaccess: Invalid command 'RewriteLog', perhaps misspelled or defined by a module not included in the server configuration
[Wed May 02 14:16:26.043954 2018] [core:alert] [pid 3117] [client 95.70.153.106:59513] /home/metehanboy/public_html/.htaccess: Invalid command 'RewriteLog', perhaps misspelled or defined by a module not included in the server configuration
[Wed May 02 14:15:42.256845 2018] [core:alert] [pid 2690] [client 95.70.153.106:59497] /home/metehanboy/public_html/.htaccess: Invalid command 'RewriteLogLevel', perhaps misspelled or defined by a module not included in the server configuration
[Wed May 02 14:15:42.256734 2018] [core:alert] [pid 2690] [client 95.70.153.106:59497] /home/metehanboy/public_html/.htaccess: Invalid command 'RewriteLogLevel', perhaps misspelled or defined by a module not included in the server configuration
[Wed May 02 14:15:34.964648 2018] [core:alert] [pid 2641] [client 95.70.153.106:59496] /home/metehanboy/public_html/.htaccess: Invalid command 'RewriteLogLevel', perhaps misspelled or defined by a module not included in the server configuration
[Wed May 02 14:15:34.964434 2018] [core:alert] [pid 2641] [client 95.70.153.106:59496] /home/metehanboy/public_html/.htaccess: Invalid command 'RewriteLogLevel', perhaps misspelled or defined by a module not included in the server configuration
[Wed May 02 14:15:21.351847 2018] [core:alert] [pid 2696] [client 95.70.153.106:59491] /home/metehanboy/public_html/.htaccess: Invalid command 'RewriteLogLevel', perhaps misspelled or defined by a module not included in the server configuration
[Wed May 02 14:15:21.351768 2018] [core:alert] [pid 2696] [client 95.70.153.106:59491] /home/metehanboy/public_html/.htaccess: Invalid command 'RewriteLogLevel', perhaps misspelled or defined by a module not included in the server configuration
[Wed May 02 14:13:47.582923 2018] [core:error] [pid 3117] [client 95.70.153.106:59459] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://ucgen.metehanboy.com/
[Wed May 02 14:13:47.582877 2018] [core:error] [pid 3117] [client 95.70.153.106:59459] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://ucgen.metehanboy.com/
[Wed May 02 14:13:46.839964 2018] [core:error] [pid 3118] [client 95.70.153.106:59457] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://ucgen.metehanboy.com/
[Wed May 02 14:13:46.839899 2018] [core:error] [pid 3118] [client 95.70.153.106:59457] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://ucgen.metehanboy.com/
[Wed May 02 14:13:39.737762 2018] [core:error] [pid 2696] [client 95.70.153.106:59446] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://ucgen.metehanboy.com/
[Wed May 02 14:13:39.737686 2018] [core:error] [pid 2696] [client 95.70.153.106:59446] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://ucgen.metehanboy.com/

Answer 1

In cPanel, you can add subdomains adjacent to your main domain, instead of a subdirectory. Why do you need that over-complicated structure? What's the benefit? Use something like this and save yourself the headache:
public_html/
|____.htaccess (application htaccess)
|____index.php
public_html_ucgen/
|____.htaccess (subdomain htaccess)
|____index.php