Shotgun desktop installation help on Ubuntu

I am trying to install shotgun desktop on ubuntu and have hit a block because of its inability to connect to git.

I have the ssh key pair for my github account and have been able to clone projects.

But when I try to install Shotgun desktop it fails with the following error:

navi@navi-Lenovo-Y50-70:~$ /opt/Shotgun/Shotgun
The authenticity of host ‘github.com (140.82.112.3)’ can’t be established.
RSA key fingerprint is SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8.
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added ‘github.com,140.82.112.3’ (RSA) to the list of known hosts.
ERROR: Repository not found.
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile

Any pointers to get this sorted would be really appreciated.