It's intended to dump the tank at sea
If it were between the toilet and the tank, there'd be no way for it to empty the tank (unless you want send it back into the toilet--which might be very entertaining, but I DON'T recommend it!

It shouldn't be necessary to use a macerator to move waste from the toilet to the tank...your toilet should be able to do that. Since it's only legal to dump a tank outside the "3 mile limit" (3 miles out to sea from the coast of the US), and you're inland where there's no place within 1000 that you can legally dump the tank, my advice is: remove it and replace any hose and y-valve or fitting in the tank pumpout line with a new piece of hose going directly from the tank to the pumpout deck fitting.And since your questions indicate you don't have much experience with marine toilets and holding tanks, I suggest you read the articles in the Head Mistress forum Reference Library and read the owners manual for your toilet so you can learn how it works. If you don't have one or can't get one, I'll be glad to explain it.