Building a long road in Minecraft means the same thing every time: dismount, walk, right-click, right-click, right-click, remount. Ride-n-Road removes the dismounting. Sit on your horse, hold a shovel, press or hold use — and the ground under your mount's hooves turns into dirt path as you ride.
Hold a shovel, get on a mount, press or hold the use key. That's the whole mod.
The paved strip is the mount's actual hitbox, projected straight down. A horse is 1.3965 blocks wide, so it covers one column when it stands dead center on a block and up to four when it straddles a corner — every column it touches gets paved in the same instant. Wider mounts leave wider roads.
Only blocks that a shovel can actually flatten are affected: grass block, dirt, coarse dirt, podzol, mycelium, rooted dirt. Everything else is skipped without costing you anything. The table is read from vanilla itself at runtime, so blocks that other mods register as flattenable are supported automatically.