Private plugins repository – failed to clone

Hi!

Recently I tried adding our nonpublic company GitHub repository to G3 Plugin Manager by adding a custom plist. The Plug-ins do appear in Plugin Manager, however I can’t install them. I receive this error:
Failed to clone repository from [repo URL] to [local path].
Knowing that items from public repos install without an issue I assume this is because our repo requires authentication (passing an access token?). Can you please help me troubleshoot this?

Thank you,
Maciej