Files downloaded from Uptodown cannot connect to Rockstar Social Club. That means no GTA Online (obviously), but also no cloud saves for single-player progress.
Uptodown scans for known malware, but user-uploaded modded APKs are notorious for containing adware or spyware. Stick to the "official" APKs (signed with Rockstar’s key) if you use the site at all. uptodown gta
The nostalgia isn’t worth the malware risk or legal headache. Files downloaded from Uptodown cannot connect to Rockstar