The comma isn't needed because you have a second verb: compose. It's clear that you're tracking the monetary and material donations and that you're composing the letters. Wouldn't make sense to be tracking (a) monetary donations, (b) material donations, and (c) composing letters. Composing letters is a separate action not a thing being acted on as are the donations.
Now if you had said, "Track monetary and material donations, and shipments," you would need that comma after donations to make it clear that you were tracking two different types of things: donations and shipments. You just happen to have two types of donations as well, which you want to group together for clarification.