My first cruise on HAL was 10/2021. I did two more HAL cruises in early 2022. On all three cruises, DH and I played in the casino.
I did not receive any “free” offers until just a few months ago via email. The majority of the offers have been for cruises at 30% off the advertised rate, and the emails were from HAL’s Players Club.
As for how much you’d have to spend, I’m not sure what the minimum rated play is for a free cabin, sorry.