This is a tough mission if trying solo.
You need to protect the Hotel from i think is about 12 waves of enemies.
Their goal is to destroy the hotel which now has a health bar for the mission.
I dont believe a specific tactic is necessary (certainly wasnt for my group lol) but try to engage enemies early so that they dont focus on the hotel but rather on the players instead.
I predominantly used the exp.50 cal and Auto4 with Armour piercing rounds the whole time.
Placing mines around the spawn points help too. The waves consist of Apocalypse Runners and Hunters.
The final wave includes a Tank too.
I tried this solo first time and hotel got destroyed on final wave, but with 2/3 people its quite manageable, just make sure you have your stimpacks and plenty ammo so u can keep on fighting. Enemies primary goal is to destroy the hotel.