Yarn: Error An unexpected error occurred: Request failed \"404 Not Found\ - node.js

Question

I´ve got an issue when I run my program with Yarn.
error An unexpected error occurred: "https://npm.pkg.github.com/download/{.../packagename}: Request failed \"404 Not Found\"".
I cloned a GitHub-Repo and installed NodeJS, npm, and Yarn.
I also create a personal access token at GitHub. And configured the registry with:
npm login --registry=https://npm.pkg.github.com
Username: USERNAME
Password: TOKEN
Email: PUBLIC-EMAIL-ADDRESS
info yarn config
{
'version-tag-prefix': 'v',
'version-git-tag': true,
'version-commit-hooks': true,
'version-git-sign': false,
'version-git-message': 'v%s',
'init-version': '1.0.0',
'init-license': 'MIT',
'save-prefix': '^',
'bin-links': true,
'ignore-scripts': false,
'ignore-optional': false,
registry: 'https://registry.yarnpkg.com',
'strict-ssl': false,
'user-agent': 'yarn/1.22.4 npm/? node/v13.8.0 darwin x64',
lastUpdateCheck: 1585820467684
}
info npm config
{
'//npm.pkg.github.com/:_authToken': `{TOKEN}`,
'always-auth': true,
`# { VALUE }:registry`: 'https://npm.pkg.github.com/'
}
Environment
Node Version: 13.8.0
npm Version: 6.13.6
Yarn Version: 1.22.4