What you have is an integration issue....
....the existing pullets are defending their territory and protecting their resources(space/feed/water) from a 'stranger'.
Multiple feed/water stations can help...make sure he gets to eat/drink.
Not unusual. If the male was mature it would be a different story.
All your birds are young, pullets and cockerel, not hens and cock(rooster) until a year old.
Your pullets are not sexually mature yet, but your cockerel probably is.
When he gets a bit more comfortable, he may start trying to mate females that are not ready and that could be unpleasant for all.
I'm curious, if you only want eggs, why did you get a male?
No need for a male unless you want fertile eggs to hatch.
Males make for complications, especially for new chicken keepers.
Read up on integration..... BYC advanced search>titles only>
integration
This is good place to start reading:
https://www.backyardchickens.com/a/adding-to-your-flock