Sliding Door Trolley Question

I’m remodeling my barn with sliding door stall fronts. Using the National Hardware strap hanger for box rails, model 5040. For the life of me, I can’t get how you can laterally adjust it if the bolt to adjust height is down in the hole drilled into the 2X. Seems like if you do it by the instructions, you only get height adjustment. Thanks. I at a standstill until I figure this out.

It’s hard to tell from the picture on Home Depot’s website. Is the door attached only through the three square holes? If yes, it looks like the bolt hole at the top isn’t circular so you should be able to move the door towards or away from you there.