why authentication in sourcetree repeatedly asking code example

Example: sourcetree asking for bitbucket password credential helper selector

To use Personal Access Token in SourceTree, you need to add your acc with this token in SourceTree > Preferences with following information:

Auth Type: Basic
Username: {your-github-account}
Password: {your-personal-access-token}
Protocol: HTTPS
After that, you are able to clone your Github repo.