They could definitely grow to be technologically advanced, in spite of their lack of fingers. You just have to be creative, and think in terms of big objects instead of small ones.
To begin with, they start breaking rocks into various shapes by stomping on them, pushing them with their noses or feet, stacking them, and then stomping them some more. It's precarious work, requiring lots of prior planning to make use of hard, precision blows, but before long they have stone objects that they can either fit around their feet by pressing into them, or the objects might have blades sticking out that pierce the hooves like horseshoes.
Not only that, but they are able to produce furnaces by hollowing out large boulders (by putting rocks on the boulders and then stomping them) and stacking wood inside them. Then they stack flint and stone just outside the furnace and stomp on it to produce sparks, and with a little work, it's a furnace!
Once they have furnaces, they can start producing charcoal and coke, which will enable them to make much hotter furnaces and eventually start melting stones in them. Before long, they are cooking metal in large stone (and eventually metal) cauldrons and pouring it into large, carefully chiseled molds.
Supposing they use this kind of thing to make armor, they may need to help each other get dressed, but dressing ourselves with armor or utilities is a habit that humans take for granted, and isn't a necessary component of an advanced society.
Now they've got metal of any shape, wool, and basically the capacity to start farming. They can melt sand to produce glass, and carefully bend metal and heat it to produce kindof makeshift straws for blowing the glass. Once they start refining copper and glass, they can rub wool against the copper to produce static electricity and then store it in (large again) glass vacuum tubes that they've just blown using big, horse adapted glass blowing stuff.
Leather is, I guess, out of the question, but it's not necessary. We've got electricity now, and it's only a matter of time before they start doping large transistors. They'll never have computers with little keyboards like we have today, but they might eventually have monitors with hoof-adapted stomping-interfaces.
Screws are by no means the only method for joining things together. The hooved society would likely just not make use of them for a very long time, if ever. They'd more likely use wedges and compression to friction-lock things together. Eventually, they might even make sap and horse hooves into glue.
We've seen humans do some pretty amazing stuff without any hands at all. If horses wanted, they could get pretty dextrous with their front limbs. I see no reason they couldn't advance significantly with enough time.