On day 20 or beyond, go visit the town you went to in the tutorial after you done the sick shopkeeper story quest, if you follow along the events happening in there, you will eventually unlock that camp to visit to, Logan should be the one that unlocks that place when asking him about it.
In case you have trouble with which town i am talking about when doing the tutorial, Bareshade is the one i am talking about that have the events that eventually unlock the camp when doing them on day 20 or further