just talk to her a bunch and play the game. im not sure when, i only discovered it after world difficulty 2, but she then offers to speed things up for 200 gems. once you get that message, just get and give her 200 gems, and it'll open.
youre given a tent and some other things after talking to the girl inside, but i dont know how to get more tents yet.
btw, idk if theres a shop that'll sell ya tents, but you can use the cheat menu if youre frustrated. I dont recommend it cause it ruins the experience, but shift+tab gives you a new option in the tab wheel, and F8 opens up a menu similar to the one in DKH. the second one, F8 menu, has some options that only work in DKH cause it was probably taken from there, but the options to alter character appearances and relationship towards you still work.
