The Runcam Split will fit our 210-R V2. The camera itself will mount to the frame using its included mounting bracket and hardware. The bracket mounts to these slots in the 210-R bottom plate:
The Runcam split has a circuit board with 30.5mm x 30.5mm mounting holes you must mount into the electronics stack on your frame. Please be aware you must account for this additional board and leave room for it to fit. The 210-R has a low top deck. This means you must use an 'all-in-one" flight controller in your frame such as the Betaflight F3. or Asgard.