The new Phasmophobia prison map' release date has not been officially revealed yet. Kinetic Games is still working on the map to ensure it functions as intended to upon release.
The prison map is available in the beta branch of the game, which can be accessed through Steam.
Phasmophobia Prison Map Release Date
Kinetic Games has not given Phasmophobia an official release date for the new prison map, but continue to work on the beta version. Players can access the map through their Steam game library.
Accessing the beta version only takes a few clicks once you have Steam opened. Select your library and go to Phasmophobia. Instead of opening the game, click the settings gear, and choose properties. Once there, select betas. A box should read NONE in it. Select it and choose the "beta unstable build."
Once you have finished the process of opting in to the beta branch, update the game and you'll be free to play the prison map.
Once on the map, make sure you know how to place items, such as cameras, and how to play using the Oculus Rift virtual gaming system to fully immerse yourself in the game and get the full, spooky experience.