Unable to open file, Box says sign out of [another user's] account

I am trying to open a file shared with me, but I get a message saying to sign out as Donna Brown and sign in again.  The problem is I am signed in as me, not Donna Brown. Signing out and back in does not work.  I checked with the owner of the file who shared it with me and it is shared with me, not Donna Brown who used to have the iPad I am using.  This iPad is not signed into an AppleID so there's no keychain to check.  Where else would those credentials be stored?  I've also removed and reinstalled the Box app, but the problem persists.