[Closed] Cassette spacer help

I'm trying to get my bike back together before it gets dark!

I'm trying to fit a 9 speed Shimano cassette onto an 11-speed hub. I took the old cassette off, and there is now a spacer on the workbench, but I don't know where it came from or where it goes - ie next to the lock-ring or behind the cassette.

Also, I noticed a spacer in the (XT) cassette between two of the smaller sprockets - I'm just keeping this where it was, but I don't think I've seen one of those before (although I've not swapped many cassettes!)

Help is much appreciated!