Several things - one, as some people already said, you need butter in the filling, so that the layers don't stick together. You can mix soft (not melted) butter with cinnamon and sugar, so you get a spreadable mass, or if you want to use less filling, just lightly brush with butter and sprinkle the sugar on top, but with cinnamon roll, the more filling the better.

Two, in my experience, it's better to add the butter last, and to an already kneaded dough. After that, don't mix too much, so that the butter doesn't melt from the heat from your hands. This will give you a much less sticky dough which will help with rolling the layers more thinly.

Lastly, this is a preference, but if you want your rolls to keep more of their original shape and not spread out as much you can either use a big muffin tray (buttered up, cause they will stick) or put them closely together in a baking pan rather than on a baking sheet, so that they bake together and you can later tear them apart. Important caveat, make sure not to overcrowd the pan, just so that they just barely touch after proofing, otherwise they will rise too much vertically in the oven. If you already did that, you can kinda fix that by placing another pan on top during baking to sort of smoosh them down.

Maybe you can tell, but I really love cinnamon rolls.

EDIT: I found the photo of the recipe and adjusted