There isn't a particular recommended doc sequence. We should make it clear in the readme.md or somewhere else.
"How to think about monetization", this is a good overview. I'd remove "Azure API Management" from the title since this is actually the content of the other doc.
"How to monetize with APIM", consider adding a simplified high level architecture diagram showing the relationship of APIM, billing portal, and payment provider. (this diagram can be much simpler than the stripe and adyen specific image)
"Deployment and initiation guide" - this is where I got lost, especially with the overlap and cross-ref to the project README. Also, I think the intent is to have steps how to create the APIM service and billing portal, without a lot of payment provider detail. Unfortunately, customer has to decide on a payment provider first, and it was confusing to me to read Stripe and Adyen details without having introduced them first. One option is to carve out common prerequisite steps as an include that can be used in either the Stripe or Adyen specific docs which follow.
Stripe and Adyen specific doc - For the Consumer Flow sections, consider adding a few screens or code snippets, otherwise it's a wall of text.
Some required files might be missing? I didn't find any generated JSON templates in the project folder. Didn't find apiConfiguration/config.yaml, etc.