Can't set upstream branch to github on Raspberry Pi


i'm trying to connect node-red on my RaspberryPi with Github, but it doesn't work as expected.
I generate a ssh-key in Node-Red and add it to GitHub Repository under Settings -> Deploy Keys.
I set up the right path for the repository in Node-Red. I generate a token on the Github Page, but when i try to push the project via commit history i don't get the authentication popup window to fill in my username and the generated token.
the log shows the error:
"could not read username for "".

The strange thing is, i did the exact same steps on my windows pc and it worked without any issues.

Thanks in advance for the help.