I just bought a bunch of games for the big deal. However, whenever I try to install any of these games, all that I get is a spinning wheel for all eternity. Cannot install any of the games I bought. Tried uninstalling and reinstalling GOG Galaxy, tried switching the drive it is on, feels like I have tried everything

Hmm. Well you could always download the offline installer files by going to Games under your account on the GOG website.

I have tried that, and it does work for some of the games, but there are some games that have about 10 different installers, each one asking for something that none of the installers are giving me

Games very big are divided in several parts but there are only one installer (or probably two if there are a 32 and 64 bits version). You must download all the offline backup parts in the same folder to install the game. For example a game of 40 GB will be divided in a small part one and ten parts of 4 GB each one. Patches usually are not necessary download because the main file is up with the last game version.

Disable IPv6 and restart your system. Report back if the problem persists. • There's only one installer (executable) per game or DLC. In some rare cases, there's a 32-bit installer and a 64-bit one. You still only need one.
• Installers for large games span multiple parts, usually 4 GB in size. You can't install the game without having downloaded the full set.
• Patches are almost never needed when downloading the game for the first time. Double-check that there's no patch with a higher version than the installer.

Galaxy should still work or tell what is wrong.

Make sure you download each file part.

Disabling IPv6 did the trick for me. The easiest way to do that is through the Control Panel.

Eh, disabling IPv6 is not an option for a lot of people.