Can't Sign In (Error Code: 400)

I'm a high school student in a film class with a teacher that wants us to use the mobile verison of Premiere Rush. The school has already paid for our accounts, so there is no problem with that. My problem is that I can't even log in. When I open the app, I'm given the four options to log in: continue with Adobe, Apple, Google, or Facebook. Because my school has already paid for our accounts, we are supposed to click "continue with Adobe". Whenever I go to click that, a box shows up in the middle of the screen saying "Can't Sign In" and "Error Code: 400" right under. I've never been able to log into the account before, and I don't know what to do. I currently have an iPhone 11 Pro, in case that means anything.