Insider Offer to Purchase Doesn't Work?

Are you referring to the Shopping Cart on the Xbox One Store? That doesn't work for me as it never completes the checkout process (I have reported it via Xbox Insider app).

Have you tried doing direct purchases on the Xbox Store? Those work for me albeit without the convenience of being able to bundle several items into one bill (ie the below $10 purchases on offer).

Some game stats and gear will work with both, but the DLC would have to be purchased on the 360 in order to upgrade to the One (if there is an offer available for it). Otherwise it doesn't work the other way around.

Is this offer limited to certain users?... I was able to get the offer ( and works just fine) but my brother said he doesn't get the offer on his dashboard. His free one month is fixing to expire and he would like to purchase that great deal. Any help
would be great!

Unfortunately for rewards offers, it doesn't work like that. You had to have actually confirmed the purchase, even if it was charged later, during the offer period which started on October 1. It didn't go by when you were charged or when the game was released.

Game pass doesn't matter. In order to qualify you have to purchase the game. If you didn't actually purchase the game, it doesn't count towards the offer.