(creating a team with shared folders)
Thats your problem - the other devices don't seem to be using *your* account, they are using their own accounts and you are using Teams to share folders.
Teams accounts do not get to share another accounts space, so you buying the 1Tb Pro upgrade will not benefit them at all.
Your other computers will all need to upgrade their own accounts, or unlink from their current accounts and link to yours (using your username and password - this is not recommended if those other computers are not yours, but if they are all yours them they should all be linked to the same account).