Hi there!
When I try to download the Valley of the Ancient demo I just change the folder for install to something like: F:\UE5 demo and click CREATE…it fails and says: There is not enough space at C:/Program files(X86)/Epic Games/Launcher/VaultCache/AncientGame_5.0EA/data
It seems the launcher wants to install the demo in the default UE folder no matter if you want to do it in a different place.