Policy settings? I ran into this a long time as well and enabling invite based enrollment fixed it.
https://centrify.force.com/support/Article/KB-9610-Getting-Network-unavailable-error-when-a-User-is-trying-to-enroll-a-device-with-a-QR-code
https://centrify.force.com/support/Article/KB-9610-Getting-Network-unavailable-error-when-a-User-is-trying-to-enroll-a-device-with-a-QR-code