I tried to check-in with the Hilton app in 2019 at a Conrad, but it didn't work. In theory, the app would have checked-in and set up a digital key for me. After using the app's messaging feature and messaging the hotel a few times I gave up and checked-in in person. Hopefully, they've worked out the bugs in their app. At least I didn't have to dig up and present my physical credit card at the front desk as the app had all that info when I made the reservation.