I can't sort my inventory on vanilla server :c

The mod relies on the server to do the sorting unfortunately. While this isn't a methodology I think is good, it isn't my mod and this mod is pretty beloved. I prefer the advanced functionality that Inventory Profiles Next provides while it is a bit more complicated. One benefit is that it ensures that all operations can be done on the client. If you need a client-sided sorting mod it might be worth looking into.