Can a MAC be used as a HMAC?
HMAC is a type of MAC. The output of a MAC is called a "tag". Not all MAC (algorithms) are HMAC.

MACs are not required to be one-way or collision resistant for someone who knows the key. HMAC, however, inherits the one-way-ness and collision resistance of the underlying hash function.

A CBC-based MAC is mentioned as a hint because it is almost trivial to find preimage values for any given tag value. That also makes collision attacks trivial.