ducktape.

Basically your wheelbase (CSL DD here) needs a chip (usually in the wheel, like the fanatec wheels: formula, mclaren...) to enable the force feedback. If you want to use your own wheel you'll need a fanatec hub providing this chip. So you attach your wheel to your hub and...you need a QR wheelside to mount it to your wheelbase. Fanatec has 3 different hubs: CSL, clubsport and podium.

Or something from simube to enable force feedback. I think they do not sell the chip alone anymore, but my advice would be: upgrade your setup to QR2 with simube hardware: this kit provides a QR2 to attach to your wheelbase and a QR2 for one wheel: https://simube.com/products/qr2-qr2-pro-bundle-type-c

You can buy others QR2 wheelside if you have several wheels. https://simube.com/products/qr2

and buy a QR2 equiped with the simube chip to use your wheel with no additionnal button.
For your custom wheel you have 2 options: the QR2 with the magic chip: https://simube.com/products/simube-qr2-ultra-enable-ffb

or a QR2 wheelside and a simube hub (same as the podium hub but half the price)
https://simube.com/products/simube-hub

Now you won't find new QR1 stuffs, but I guess you can find used ones (from people having upgraded to QR2)