Can you use Orbi AC3000 satellite with AC2200 system or create dual networks with DOC 3.1?

You can use any RBS satellite between the RBK20, 30, 40 and 50 series systesm. It's best to keep RBS20 and 30 and 40 series with the same 20/30/40 series systems as the connection rates are all the same between the router and satellite. The RBS50 and RBK50 systems have higher connection rates and its best to use RBS50 with RBR50 systems. 

DOCSIS is a cable modem only protcol standard. Something the RBK systems don't work with in. RBK systems connect to any ISP Modem, cable, DSL or Fibert ONT device which interfaces with the ISP services. 

If your ISP interface device already has a built in router and you want to add the Orbi system, you can have it connected and have two different networks. However for simplicity and ease of use for new or average home users, it's recommended to either use the ISP modem as your main host router and add the Orbi as a AP mode configuration, or bridge the ISP modem and use the Orbi has your new main host router and wifi. Having two routers on the same line can cause problems. 

Modem Combo Units:
Couple of options,
1. Configure the modem for transparent bridge mode. Then use the Orbi router in router mode. You'll need to contact the ISP for help and information in regards to the modem being bridged correctly.
2. If you can't bridge the modem, disable ALL wifi radios on the modem, configure the modems DMZ for the IP address the Orbi router gets from the modem. Then you can use the Orbi router in Router mode.
3. Or disable all wifi radios on the modem and connect the Orbi router to the modem, configure AP mode on the Orbi router. https://kb.netgear.com/31218/How-do-I-configure-my-Orbi-router-to-act-as-an-access-point and https://www.youtube.com/watch?v=H7LOcJ8GdDo&app=desktop