How many users can use the program at the same time, but from other devices?

Hello there, accounts435.

QuickBooks Online can be accessed by multiple users at the same time from other devices. However, the changes made will not directly flow into the account thus, they'll have to refresh the page to sync the changes.

I've also added this reference that has information when managing users: Learn about user types in QuickBooks Online.

I'm just a post-away if there's anything that I can help. Keep safe!