I just encountered this problem a few moments ago, for the very first time.  
I am running Verbum on macOS.  When I click the Verbum icon to start Verbum, I get the small window that asks me to sign in using my Faithlife account. I enter my email address and password, but the "sign in" button remains grayed out, so I cannot start Verbum.  
Any ideas as to what is going on and how I could address the issue?  Thanks!