Zoom-Salesforce integration not working

I've integrated Zoom with Salesforce as per the instructions provided by Zoom, but when I try to sign in to Zoom from Salesforce  by clicking the phone icon, I sign it, but it gets this error " Attempt to de-reference a null object".
It says I have successfully logged in, but it gets stuck on loading, while back in Salesforce, it still asks me to log in. Any ideas?