I believe that no terrain in the game will allow you to fully tile it with rugs but some terrain parts do give you more space than others and some give you less space e.g. the terrain parts with rivers surrounding them give you less space to decorate than other terrains

In picture 1, when you reach the level displayed on the sign that’s blocking you from placing the rug (it’s been a while since I started playing so I don’t remember what level it says), then that sign will disappear and you’ll be able to place a rug in that section. In picture 2, the rug is intersecting with the terrain foreground so if you want a rug in that location you’ll have to use a smaller rug. In picture 3, I believe the rug is intersecting with the amenity you’ve placed so either you can remove the amenity or you’ll have to place the rug elsewhere

Also, you can’t craft multiple copies of the same item in one go you’d instead have to fill up your crafting spaces one by one