I need it ERM compatible pls

it works fine with ERM, I'm playing with ERM, explosive bitter, toxic bitters, armoured bitters, this mod.

You need to make sure you keep "bitters" spawn in starting settings, other wise it will never spaw anything that is not bitter.

not for me... nothing is spwaning i use 4 slpit - and only normal biters are spawning in the area with vanilla bitters

pretty sure is something else making them not spawn, make the basic test, add only ERM, then the bitter mods you want.
It does not work with some mods like natural evolution or bob enemies when parried with ERM, since they replace they spawn mechanics. Also make sure you are in the proper area, it has terrain check to spawn on desert.