Where did you order the cassette from? I was looking and went to order from R2-Bike.com but they had this at the bottom of the page:
“Note: Garbaruk XD cassettes are not compatible with all rear hubs (eg Hope Pro 4 hubs)!”
After a lot of research I deduced that Hope do 2 versions for the Pro 4 Freewheel, one for their own cassette (which the Garbaruk cassette doesn’t fit) and one for Sram cassette, and I luckily had the Sram freewheel. Garbaruk also quote a max diameter on a part of the freewheel, 21mm I believe, I measured mine before ordering and it was 0.1mm less than their max so went for it and it fitted perfectly. I have seen on the net that owners with the Hope Cassette freewheel file this piece down, bit of a bodge but works. Oh, and I ordered direct from Garbaruk website direct.