1. The prepaid booking will come through to the hotel looking like an OTA booking (Expedia), so while you might get lucky and get stay credit, it is not supposed to qualify
2. The Hotel Collection $100 credit is a credit applied by the hotel at check out against on property charges that you are able to charge to your room (i.e. dining, spa and sometimes parking, though parking will depend on whether you can charge it to your room). Since you mentioned you are staying at a Four Points, I would evaluate whether there is $100 worth of incidentals you would spend at the property. Also, if you are thinking of applying it against dining charges, I would also check that the hotels F&B outlets are open.
3. If you don't go the prepaid route, the hotel should be willing to let you use any Amex card in your name at check out.

Also, out of curiosity, what Four Points belongs to The Hotel Collection? My first reaction was that it doesn't sound right, but I suppose there are international Four Points locations that might be more upmarket than what we have in North America.

(But I'll note that at first glance I don't see any Four Points locations on the list. Are you sure you aren't just looking at a plain vanilla booking using Amex Travel online?)