A single XMPP server can do 500 sessions, but each webbridge is limited to 100 for example. I would strongly recommend you move to 3.X where XMPP is now longer and there is increased scale, beyond the 500 support by XMPP.
I recommend setting up the IVR in the API, api/v1/ivrs. If you set the IVR on webadmin is specific only to that callbridge.and you can only set one on the webadmin
The credentials you provided for the CMS on CMM are incorrect so it can't talk to it. Make sure the credentials are correct / the account has not expired.