Avoid any car waxes that look milky or sort of like Milk of Magnesia. Those have a super fine abrasive in them to aid in removing swirl marks. On a matt finish it's near impossible to buff away all the white abrasive so it ends up looking chalk'y. A real mess. If the instructions say to rub on then wait for it to go hazy then buff off there's an excellent chance that it has some of this white polishing compound in the wax. And certainly as mentioned any reference to "polishes as it protects" or "Removes swirl marks from cleaning" or words to that effect is good evidence to avoid that one.
Actually there's really no need to do ANYTHING to it. But if you want to protect it a bit then use a transparent wax product. Plain Johnsons paste wax would work. Just wipe on, wait a few moments for it to dry and buff off the excess.
Another product is Eagle One Nanowax. It's a clear liquid that goes on and buffs off all in one go. It shines up my new car lovely and the spot I tried on my matt finish motorcycle tank came out looking just a tiny bit shinier than stock. Still very much matt. Haven't done the whole tank yet but it seems good enough that I'm going for it the next time I clean the motorcycle.