Ward Prime is full of unique root monsters in Remnant: From the Ashes, and you need to learn what happened here in the DLC Subject 2923. To advance further into the facility, you need the Ward Prime maintenance key. You can find the key in the medical bay.
To gain access to the medical bay, you need to find the glowing red orb of power on the main floor. When you interact with it, the orb teleports you into a strange world where you can interact with certain things in Prime Ward. The spectral monsters wandering the hallways can now see you too, and they can attack you. Unfortunately, they don’t die. It’s better to rush to the Medical Bay door and shoot down the obstacle in front of it, returning to the real world. You can now proceed downstairs.
You have to do the same for the medical bay on the lower floor. The glowing red orb that teleports you down there will be closer to the back area of the medical floor. The obstacle you have to destroy this time is closer to the entrance, to the right of where you first enter the lower level.
After you destroy the obstacle, you return to the real world. Proceed to the left until you see the Medical Bay sign, and there should be an open window to your right. Jump through it, search the room, and then destroy the bookshelf located in the far back. The key is on the table the bookshelf had been blocking.