Self Activation

I connect my laptop to the modem i just purchased and I get a "WalledGarden" page telling me to use the xfinity app.  I go to my phone and open the app, put in the CM MAC and it sits for quite a while then says something went wrong.  The modem is a MB8611, it is obviously connecting to the network if I can get to a page saying I need to activate with the app.  I cannot find a phone number to call for support so here I am...

-rich