Assuming the process works correctly, the front desk has zero to do with OLCI/Digital Key.

Everyday at 12:06pm local time, the first sweep of the day is done for the people that have requested their keys and if the room is vacant ready, you should have the key at that time. After that initial sweep, the PMS system continues to do sweeps/will provision keys as rooms are turned vacant ready throughout the afternoon.

What holds up the keys from being provisioned? The MOP on your reservation declines. The room you selected hasn't been turned vacant ready yet. Your reservation is flagged for ID verification by the PMS system where the desk agent needs to verify/attest (click two extra buttons) that they checked your ID before manually provisioning you a digital key.

Can you get a digital key earlier than 12:06pm on your date of arrival automatically? No. Can a desk agent check in your reservation and then provision the key to you prior to that time? Yes.