Was not able to install extension.

The same stack is happening here - happy to help test any proposed fixes!
This is one of the rare case when GitHub Extension for Visual Studio online has a lower version (2.7.1.6591) than the one shipped with VS 2019 Preview (2.8.0.6762).
If we can get a new release of the online extension with a higher version, this should work. In the mean time, a work-around is to install the one shipped with VS (by searching for GitHub in Quick Launch and click on the Install GitHub extension result).
@Huy-Nguyen-MSFT thanks for providing that workaround.
We are planning to ship a new version of the extension on 02/25.
This should be fixed now. @Lupusa87 @NickCraver hope that you will try to install the extension again!
@meaghanlewis Works great now, thanks for the fix and the poke!
thank you
thank boss