This mod speeds up trading with villagers a lot, by changing the meaning of the buttons in the trade selection GUI:
- Clicking a trade will execute this trade once (instead of just preparing it)
- Shift-clicking a trade will execute it as often as possible (until either the villager locks the trade or you run out of trading materials)
- Ctrl-clicking the trade will prepare, but not execute it (the default behaviour of the selection buttons)
Older versions of the mod (before MC 1.14) brought their own GUI, as those versions didn't have a quick way to select a trade. With 1.14, this GUI got removed. If you've been using one of the older versions, don't think the new version doesn't work; it just doesn't show the GUI anymore as there's no real reason to have it.
The mod generally works with servers as well. If it doesn't with yours, your server owner may have some AntiCheat plugin enabled; there's not much I can do in this case.