I need ideas for what to put under the cat’s pan.

A piece of scrap carpeting will help litter from tracking everywhere.

I cut a card board box down in the front and a bit back one side, put in a double bottom with another cut piece, and also cut sides from more. Thus you have bottom back and sides all double card board, and the plastic cat box sits on it, and I slide it out to clean. Any 'accidents' that get some of the cardboard wet, simply discard it and put in a new piece. Works for me since 1986 and two cats.

We used one of those “pee pads” that is for dogs kept inside all day. They look like grass pads. Just set it at edge of the liter box. Worked great for us.

https://www.petsafe.net/learn/how-can-i-stop-my-cat-from-getting-litter-everywhere

I had the same problem, AND my new re-homed dog kept raiding the box for gourmet treats - yuck. I went to my local pet supply store and found a cat box that looks like an igloo. The round plastic top comes off for easy cleaning. My cat loves it. I still have an occasional problem with the little dog trying to sneak in. But, no more scattered cat litter except for a few tiny bits of clay that gets caught on the cats furry feet. The cover hides the ugly daily mess, contains the odor and everyone is happy. Except the little dog who no longer has license to an open buffet of kitty poop.

Right now in the stores there are large rectangle plastic holders meant to hold wet boots and shoes at he door. You can sit the litter pan inside one of these.

I just purchased a mat made for the purpose at the pet store. It has ridges, and most of the litter comes off kitty's feet onto the mat as she walks away from the box. When I change the litter, I take the mat outside and shake it off and rinse it, if necessary.

While I have a VERY old digital camera, I have no idea how to get it in the pc.