It can be a bit confusing and worth a read of the manuals to familiarise yourself with connection options.
To get you started.
CD5X. Remove the link plug and connect a SNAIC5 between the Upgrade socket and Flatcap 2x Power Out B.
Stageline. I’m assuming you have the Stageline Output 2 connected to the 202 Aux2 in & pwr via a SNAIC5?
To use the Flatcap 2x, connect Stageline Output 2 to Flatcap Power Out A via a SNAIC5. Connect Signal Out A to the input socket you want to use on the 202 (say Aux2 in) via a 4 to 5 pin DIN interconnect.