Hej Bo,
The CCA does not care for/depend on the speakers used in the setup.
You’d connect it to the Core!
But......the Core has already ChromeCast built-in - you don’t need the extra device.
Just open the app, that you want to use and click the Cast icon to choose your Core.
If correct set up, you don’t need anything/to do anything else - the speakers will turn on when the Core receives a sound signal.
P.S. Save/keep your CCA device for another setup sometime....these small devices are discontinoued and are getting rare.
N.B. In case you have tried to connect the CCA directly to the BL20’s.....I would not recomment that.
You’d need cables there anyway.
The Core gives you all that you’d need for wireless connection from your phone/tablet/laptop.
If you don’t want the PL cables to the BL20’s, the only option will be the Transmitter 1.
P.P.S. If you don’t already have a BeoRemote One - I would highly recommend it for controlling the built-in sources of the Core (e.g. Netradio) and for volume controlling.
MM