Ok, I opened the Rataje level and looked at how the AreaFiller was created, and finally I understood how it works, it’s how I thought, but I hadn’t done an important step:
The first thing is to select the area on the ground, then in the “Area Filler” tab create a group, this can be composed of more groups, which is quite advisable to have everything sorted by categories if several Area Filler are going to be used, and within that group create a new Item, that Item will be one of the models that will be repeated throughout the Area, the first option to modify the Item is called “Object” in which the path of the model can be pasted, for example a tree .
Then select the group and click on “Fill Picket Area” and that’s it!
I hope it was understood if someone else did not know how to do it.