Hello, I just got a PC and the builder installed the Witcher 3 GOTY for "free." I messed around a bit and did some saves early in the game (15 minutes in) and then went to actually buy the game myself. I uninstalled the "free" game and then bought and downloaded the one from GOG.

When I load it up I can play it but I can't make a new save. Even more strange I see the old saves and checkpoints from the "free" game. Can someone point me in the right direction?

In many cases it's a question of missing permissions (virus protection, security suite, Windows defender). Set the games to the corresponding exception list.

For further details read this thread; especially #5 may be helpful:

https://forums.cdprojektred.com/index.php?threads/saving-problems.10965917/