Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[Snapper]

No idea where to start creating a jig plate for these cases.

If it's specific for one part then your imagination is the limit. You just need a method to quickly and accurately place the part on the jig, some sort of reference to touch off, and a way to hold it. As a couple of examples, if you have holes or can find somewhere to put extra holes for dowels on what will be the bottom face that's a really easy and accurate way to do it. You could cut a pocket in the plate for the part to sit in. Could even just have a straight edge in each X and Y to butt the part up against. And just a way to hold it down, step clamps, bolts directly through any through holes etc.

The amount of time this could save you compared to flipping and touching off each part in the vice for every single op could be substantial, leaving you only needing to set up for each op once at the start of the day. So you'd use some sort of reference in your vice to line stock up with and cut so many parts from one side in the vice, then set up once on the jig plate and do all the flip side. If you see what I mean. Save your work offsets for your vice and jig work as G54 and G55 then when you start your machine the next day all you have to do is chuck up your edge finder/probe or whatever you use and make tiny adjustments to account for the error in the home switches at the start of the day.

For batch work on a machine like this with the tools you have I can't think of a better way to do it.