The tricky part with all-points rental is you don’t get credit card insurance coverage, while adding the daily fee for insurance negates the free rental part completely.
To initiate CC coverage you need to charge that rental to the card. A free day / week show up as a coupon deduction. Personally, I either add one paid day or ask for a paid upgrade during pick-up. That way the insurance is triggered (confirmed that in a call with AmEx a few years ago)