Cossack

It's not a Horton problem. Most off-the-shelf quivers require a (often unique) mounting plate to attach it to the bow.
The quiver that come with the bow when sold as a package comes with the plate, otherwise you'll need one that fits that bow and that quiver. (It's like car oil filters, each has their own) Some bows (e.g. Cyclone) require an additional bracket between the bow and plate. For best results, take the bow to someone who not just markets quivers but has or can order the appropriate plate to fit your Horton.