Cannot Login to xFi app with website credentials

Hi - New xFinity internet customer here, trying to setup my new service. I cannot get past the first step of logging into the xFi app on my iPhone.   I've been trying for hours usingthe same (non-comcast) email address and password I use to login on line in my browser.  All I get is the message that my id or password is incorrect - while I am repeatedly able to login on my laptop. 

Any suggestions are appreciated.  I've deleted and reinstalled the app, restarted my phone, cleared my history and website data in Safari and reset my advertising ID in Privacy.   Thanks.