Actually, I think it is the
Flat Mount version we are interested in. They have 2 separate manuals. Strangely the two versions, FM and PM, take different pads. The flat mount (FM) version takes pads which are compatible with Shimano K-Type pads, the post mount (PM) version takes Shimano G-Type pads.
The K-Type pads include the Shimano BR-R9170, RS805, RS505, RS405 and RS3305 according to the Riderever web site. Shimano shows a bigger range of compatible models in the K-Type range.
The manual is at
https://www.riderever.com/archive/download/seo/MCX2-FM-Manual.pdf