First time using encoders

hi all, it’s our first time using encoder on our drive train.
we have the AM-2899 absolute encoder and WCP DS Gearbox.

how would you recommend us to connect the two?

It does not seem like the WCD DS Gearbox has an encoder mounting point.

This might help:

Ideally, you want to connect it to the output shaft. If you have to mount it to an input, then your code can do the math to figure out the output.