This page is regarding the PC Rift version of the game.
Found using API Monitor, when the game calls function ovr_GetLoggedInUserID it gets a result of 0 instead of something else, which seems to prevent it from doing other things it needs to startup.
The dumbest/easiest way I've found to get past the issue is to NOP out one of the calls from DCVR-Win64-Shipping.exe which allows the game to start, already purchased DLC will work, but the game will act offline (like Quest 1 version) and offline leaderboard will show name as “None”.
Patching DCVR-Win64-Shipping.exe version 1.2.2:
The LIV/Mixed Reality using Mods page has the notes regarding the modified version of Revive (https://github.com/Jas2o/Revive-ExternalCamera) that allows SteamVR users to use a tracked camera with Oculus MRC games.