This means they use six of the nine holes in your sprocket. But are the holes in your sprocket 10mm diameter? You can open them up. It isn't a problem. But
You might also want to ask them about the BCD. BCD is Bolt Circle Diameter. Are the nine holes in your sprocket centred on the correct diameter to line up with the 10mm holes in the top hat adapter?
Im not saying they are different but you might as well know for sure.
I'm sure they would prefer you buy a new sprocket from them too and they should have lots of tempting sizes to buy and experiment with!
The prices for MB sprockets are generally speaking pretty cheap.
But you probably want to know beforehand if your kit sprocket is completely compatible, adaptable or not practically very compatible at all.
BCD is important. If holes are just slightly different BCD then drilling to open them out is just about impossible, and filing out the holes
and opening them up a bit,
accurately, might just be too much PITA for you. I'm sure it could be done, it's just whether you want to know that you have to!