I have 2 servers on the same machine, one is Bedrock and the other is Java. And on Bedrock, Dolphins and down are everywhere. But on Java, I haven't seen a single dolphin or drown. So my question is where and the dolphins and drown?
What version of Java are you running?
Anything earlier than 1.13 won't have them.
Are you looking in the ocean? In Java drowned don't spawn in rivers and swamps (according to the Wiki at least.)
And apparently they don't spawn in Warm Oceans though I'm not sure of that.
Any time I hang out in the ocean in Java 1.13.2 I see drowned, dolphins are more random but I do see them every once in a while.
I probably misread the Wiki, I expect it was just swamps that don't have drowned in Java though I'm not absolutely certain.
(Since the Aquatic update I have been spending most of my time by the ocean so I couldn't say if I've seen drowned in rivers.)