You want to use coarsely ground beans so they don't get through your filter into the coffee. It's okay to cheap out with this stuff: https://www.amazon.com/Gevalia-Guatemala-Coarse-Ground-Coffee/dp/B07J5K3W43/

Regular (dunkin or other) grounds wouldn't be the end of the world, but you'd have more 'grit' in the coffee. Buying whole beans and grinding 'em up yourself is a good next step for you.