can I use Motion 5 in my 2015 MacBook pro. I am using FCP 10.4.8.

Yes, you can. I have used Motion on my 2014 MBP for years, right up until last month (and that is because I got a new mac :-)).

That list is just for cards that may be added to macs, it does not mention those that already ship in them. The ones that ship in, for example, on the 2019 16” MBP are also not on the list.