After I created the ThinkWrap GitHub account and uploaded the public key, this key got somehow bound to GitHub identity ‘madamy’
I had to add user madamy to my public GitHub repo - where I keep the dot-files - https://github.com/radegast/dotvim
This may be an issue for people that have their own private accounts - the key management is the key.
This article is useful:
Use https for forking , instead read/write ssh. No keys involved there
Author Miro Adamy
License (c) 2006-2020 Miro Adamy