You can convert the supplied MOA dial that comes with the CDS scopes into a zero stop yourself, it isn’t hard and doesn’t cost more than a few pennies.
Now that you’ve noticed the little tab you’re halfway there. It just needs something to contact it. The way I do it is with the dial off I’ll eyeball the distance from the 0 to the edge of the tab and note where it lands on the quarter MOA marks. Flip the dial upside down and you’ll see a raised portion around the outside with a groove in it and a small hole that isn’t in the right spot to do you any good but would be where they put a ball on the custom dials. Using the reference distance you noted on the 1/4 MOA marks drill a small hole and tap for an Allen head set screw. I used 4/40 but it doesn’t matter much, it might be easier for you to go metric, depending on what taps you have available.
There you go; free MOA dial with a zero-stop. Easy as falling down a well.