Do you have the ZAC-60 unit in each room with speakers? That seems to be your source selection piece and the key to getting everything to work. You should have options on the ZAC-60 to select a source.
You do want to make sure you really do have all the parts and pieces so beyond the ZIM-4, please give a full list of what you actually have and where everything is.
For example:
Bedroom 1: ZAC-60 & ZIM 4 & Speakers
Bedroom 2: ZAC-60 & ZIM 4 & Speakers
Basement: ZR-98
Check that lights come on on all the products which should have lights, especially the ZR-98
The ZAC-60, as the controller, is fully described in that manual which you think is overly technical. The reality is that it covers a lot, including the ZAC-60 with details of how to select a source.
But, which sources were programmed is up in the air and unknown to us, so you have to use it and see what sources you can select from the ZAC-60.
Follow the instructions on page 8 of the manual as it tells you how to select a source. This should allow you access to any ZIM 4 or a source plugged in directly to the ZR-98, but those sources will be dependent on programming of the ZR-98 and the ZAC-60 units.