I also have a 2019 with a 3dmaxpider cargo mat. There are two flat spots on the mat that correspond to the rear flip up cargo hooks in the trunk. If you use an Exacto knife (or any sharp hobby knife) you can make 2 slits in the mat to make a tab that flips up allowing you to use the cargo hooks underneath. Not sure why the manufacturer did not ship the mat with accessibility but I imagine it was an extra step, cost or feature not considered.
In addition to the large cargo net I have two smaller cargo nets that attach to the backs of the seats in the cargo area that are terrific for smaller items. Widely available and relatively inexpensive. Example: Small mesh cargo nets. I own this set and they are great to keep the smaller items from rolling around.
It’s been a few years, but amazon has several kinds. I’m not sure if this is what you’re looking for, but I find mine helpful.
Universal Mesh Cargo Net https://www.amazon.com/dp/B0836J292B/ref=cm_sw_r_cp_api_glt_fabc_JCZ7G8KHJKGJRR1ZWCQK?_encoding=UTF8&psc=1