Find a way out of the building
After you've finished speaking with Lev, dive into the pool to find a Coin 20/32, then go through the gym to find Orchards Juice Bar, now go into room behind the counter to find an Artefact 100/117 pinned to the wall. Go back out into the corridor and open the green door behind the desk to find a safe, input 12-18-79 to open it and then you'll find some Supplements.
Unlock every safe
From here, go through the exit door and then head downstairs and open the door to initiate a cutscene. After the scene has come to a close, head through the gap in the wall on the right, then go into room 1904 to find a mask for Lev, now explore the other rooms for ammo, resources and supplements before returning to Lev.
Once you've given him the mask, head back into the room and lift Lev up to the area above to retrieve a rope, now throw it down the hole and rappel down. Upon dropping, go into the room on the right to find an Artefact 101/117, then follow the narrow path ahead until you can drop down another floor.
Continue through these next few rooms until you reach another area to drop down, then go into the bathroom on the right and walk along the beam to find a body with a Flamethrower. Drop down another floor and follow the room around to drop again, here you'll want to take the beam over to the right and jump down.
Take out the enemy, then grab the Supplements from the desk and a Coin 21/32 from the room behind you, then go into the room on the opposite end of the beam. Continue dropping down until you have to force open a door, then once you've taken out the enemies in the area, jump down the lift.
Here you'll want to go left to find a Coin 22/32 in the vending machine, then go outside and drop down to find a bar. Grab the Coin 23/32 from the counter, then continue onwards the Hospital. Finally, go into the Specialty Care Center for another Coin 24/32, then go into the building for a cutscene.