Are you wanting to use the 4 ceiling speakers as surround speakers to create a multi-channel setup? If so, I don't think there's going to be a clean or well-integrated way to do that with the Soundtouch 300, IMO. It's really only designed to work with the VI300 surrounds for multichannel audio. Sure, you can do tricks with a receiver to essentially overlay two surround systems. But it kinda defeats the point of having a clean soundbar setup, and just increases the chances of having audio issues (channel levels, delays, etc.). In this situation, you would be better off buying a passive soundbar and using the receiver to handle all the multi-channel decoding and power the soundbar + surrounds together as one system.
If you're wanting to use the 4 ceiling speakers to distribute audio throughout the house (e.g. Spotify music), then I would return the receiver and instead buy a Bose SA-5 amplifier. It's designed to integrate passive speakers in the Soundtouch ecosystem.