A bit confused setting up my 4 Channel Speaker Selector for multi-room audio…

I purchased this - https://www.amazon.com/dp/B07MK59T3F?psc=1&ref=ppx_yo2ov_dt_b_product_details

To work with my Denon AVR-S760H receiver. The sole purpose of this receiver is to supply amp power to these 4 zones speakers. I use the HEOS on it in conjunction with my main home theater. So no video but set everything to play MONO.

The wiring of the selector is confusing me though as this is what I have…

Zone 1 - 1 Bathroom Speaker plugged into the R side, L is empty.

Zone 2 - 1 Bathroom Speaker plugged into the R side, L is empty.

Zone 3 - A pair of outdoor speakers plugged into R/L side

Zone 4 - A pair of outdoor speakers plugged into R/L side

First is this wiring ok? Is it ok to put bathroom speakers alone if it is playing in MONO? I don’t have a PAIR for a zone…I need them separate.

The part that confuses me is the AMP connection. When I have A-AMP going to let’s say SURROUND L/R (zone 2), the A/B selector works as intended and everything is controlled on zone 2. But I need to plug in the B-AMP correct? So I plug that into let’s say FRONT/L (main zone for outdoor speakers). But then now the pair of outdoor speakers, when I click A/B they switch between one another. Everything gets wonky.

I understand that the button switches between AMP A/B which I guess means each pair of speakers turn into their own individual? What am I doing wrong or is this how it has to be?

Am I better off getting TWO 2 channel speaker selectors?

I want my bathroom speakers (2 individuals) to be powered separately with zone 2 on the receiver and I want my outdoor speakers (2 pairs, 4 total) to be the main on the receiver. But seems like the speaker selector may be confusing it?

Thank you!