After regrouping with Alejandro he will give you a mask where you need to make your way to the penthouse. From where you are, walk forward past the swimming pool on your right until you get to a gate and an outdoor kitchen area. Once here, pickup the bottles. Make your way through the gate and you will see a tree in the middle of the path, just after this there will be an outdoor balcony. Climb up the outdoor balcony to get inside the building.
Once inside, go up the stairs and through the 2nd door in front of you. Once you've gone through the first door you will see a corridor that has a red light in it. On your right go through the next door and you will see the outside of the building. Climb over the barrier and turn right, next climb up the ladder onto the roof.
Once on the roof, turn right and make your way to the right side of the building on the outskirts to avoid enemies. Once here, you will see a ladder in front of you. Throw a bottle onto the roof of the building you are on to distract the enemies. Once the enemies are distracted, crouch walk to the ladder. After climbing the ladder you'll regroup with Alejandro and will jump down onto the elevator.
Press the yellow button to make the elevator go down, when you see the first elevator door press the red button to stop the lift. Look upwards to find the emergency lock to open the elevator door.
If you are still having trouble, feel free to use this video as a reference.
Hope this helped, thanks again.