Hey guys!
Having a problem with github integration.
Installation goes smooth, but when I click 'Get Started' the page tries to load github stuff but then shows this ambigious error:

I tried digging a little into networking activity and found request that fails with 403 
What has been already tried:
- Permissions checked, and granted org adming and jira product admin
- Reinstalling application
- Installing from github side (ends up with same 403 error)
What could be the case and what I might've missed?