I’ve tried multiple versions of transferring the tackle, but none seem to work. I don’t know if it works passively in the background or if I just need to do something specific, but I’ve tried long pressing, double-pressing, and pressing them both at the same time. I can’t imagine any other way. Could someone help? :(
Only the Iridium Rod can use tackle. You'll have to obtain this rod if you don't have it!
Then it should be as simple as dragging the tackle on top of the rod in your inventory to attach the tackle.