Can't authorize device

I have Adobe Digital Editions on my Samsung Galaxy S9 phone. For a long time I used it with no trouble. Now every time I try to read something, I'm told that I have to authorize the device. I've given it my Adobe username and password over and over and over again (checking to make sure they're the right ones); it doesn't accept them. I tried uninstalling and re-installing ADE; no luck. I'm at my wits' end. Help!