with another AUR helper
I get this message/error - which might be more helpful:
The authenticity of host 'github.com (18.104.22.168)' can't be established.
RSA key fingerprint is SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
You must register at unrealengine.com and link your github account to access this private repo. See the wiki for more info: https://wiki.archlinux.org/index.php/Unreal_Engine_4
:: Exited unreal-engine build early
The essence (to me):
you are not even allowed to download the source files without registering
It appears that the vendor has changed the repo from public to private.
==> ERROR: You must register at unrealengine.com and link your github account to access this private repo. See the wiki for more info: https://wiki.archlinux.org/index.php/Unreal_Engine_4
Error: Failed to build unreal-engine
You will have to follow the vendors instruction on how to get the sources before you can build the package.