What can we actually put on sites heated floors?

We just bought a house that had schluter/ditra heated tile throughout the entire house. Initially we were really excited about this but then the owners told us we should not have any rugs or anything big covering the floors. I like the idea of the floors but I’d also like to have some rugs in the house and I can’t really find much info online. My question is what is actually ok? What about my dogs bed? A front door mat? Bath mat?