I do not know how to get salt without crafting it with prismarine shards and making the ore. How do I get it normally? I know it spawns near rivers but that is very broad.

It is very hard to find it in rivers too. Maybe the rarity could be decreased. I do see that the current as of writing version (Minecraft 1.16.5), this is addressed by allowing to create by using stacks of water bottles

In 1.4.1 on CF (both fabric and forge) it can spawn as often as clay in RIVER biomes only. minecraft:river and minecraft:cold/frozen_river whichever the frozen one is called. There is also the ability to craft it manually using the water bottles we added.