The breach didn’t happen quickly because LE changed their tactics when the shooting stopped.
At that point it went from an active shooter to a barricaded shooter, meaning they had time to bring up the equipment they needed to make entry safely.
The first officers to the room were patrol and K9 guys, who didn’t have entry equipment with them. They needed to wait for the SWAT teams and their explosives, because you just can’t defeat a hotel room door lock with your feet. Not a modern one, anyway.