@o0RatBois0oThe only limitation is that you can not be logged in at the same time to the same account from two different computers.
But access to the Gallery will not be given if you register an account in Origin and you have written that you are under requirement age.
Another reason may be mods in the game or broken settings in the game folder
For now, If you have any mods move the mods folder to the desktop.
Delete localthumbcache.package file in the game folder and fix the game in Origin.
Origin/Library -right click on TS4 - option "Repair game"
You have to wait until Origin will fix all packs, not only the base game.
If you don't have CC or mods delete this file and fix the game also. The game will create the same new file but without saved errors.
Turn on the game to create a new, empty mods folder. Check if a game is working now without mods.
Then copy from desktop your mods and CC and paste it in the new mods folder.
First, paste script mods every time checking if the game is OK. Do the same do the same with CC but if you have a lot of this, try the 50/50 method
If it doesn't work then we'll try to do fabric reset of the game folder later. But first, try what I have written above
I don't work for EA