MU-MIMO question

A common explanation for MU-MIMO is AxB:C where A is the number of receive antennas, B is the number of transmit antennas, and C is the number of spatial data stream.

Is C also the number of radios on a wifi system?

AP302W e.g. have two radios, each which 2x2. Does this make it "2x2:2"?

AP302W:https://documentation.extremenetworks.com/wireless/AP_Guides/AP302W/GUID-8E765D09-9A9F-4FF1-AE81-8A32F9215D34.shtml