Rug rucking terribly - what’s the answer on carpet

[Smellslikeperfume]

I got a lovely washable rug but it creeps all hi itself and the rucking is rucking awful.
I don’t want carpet tape as the carpet under it it lovely and new but it’s insane. Has anyone stopped a rug creeping on top of carpet. It’s a fluffy one from Wayfair. Checked. I can’t seem to link.
Machine Washable Shaggy Boho Grass Green Area Rug

https://www.wayfair.co.uk/rugs/pdp/17-stories-machine-washable-shaggy-boho-grass-green-area-rug-u110581061.html

An anti slip rug should help.

https://www.dunelm.com/product/rug-anti-slip-mat-1000002949

It's the carpet, not the rug.
We had a rug on the old carpet in this house, and it didn't move an inch. Replaced the carpet, and the rug wrinkles drive me up the wall!

Anyway, looking for suggestions, as I've also ruled out tape.

I’ve never had such a nice carpet before. Hoovering (sorry vacuuming ) leaves marks ! This is new to me. Maybe it’s just rejecting the idea of being covered up?!