@Ingo_Richtsmeier, i was getting below error when i push to upstream branch.
aravindh@ARAVINDH-RS MINGW64 /d/opensource/camunda/camunda-docs-manual/camunda-docs-manual (aravindhrs-camunda-docs-manual)
$ git push --set-upstream origin aravindhrs-camunda-docs-manual
Username for 'https://github.com': aravindhrs
remote: Permission to camunda/camunda-docs-manual.git denied to aravindhrs.
fatal: unable to access 'https://github.com/camunda/camunda-docs-manual.git/': The requested URL returned error: 403
Also i have created a ticket for this discussion: https://jira.camunda.com/browse/CAM-11717