I've never had it work at any Marriott in any country or brand, pre-, during, or post-covid. I use an Android. The app always asks me if I want a Mobile Key, I select yes, and I never get it. I always have to go to the front desk.

Hilton is like a 75% hit rate for me - the Digital Key working the first time when I go directly to my room without stopping at the front desk - and they've had it up and running for about five years now, pretty widespread.

I cannot understand why Marriott can't figure this out. I mean, I would understand if they just said "we're never going to invest in this - it isn't worth it to us". But the fact that they seem to have half-tried it, still talk about it, and it never works is bizarre.