Painting after removing wallpaper

I am finally removing the really ugly wallpaper that came with the house, and I need help on how to prep my walls for paint.
It’s a bathroom that had vinyl wallpaper installed when it was built in the mid-80s.

It was vinyl wallpaper over a single layer of flat paint, on sheetrock.
As I was steaming off the wallpaper, there was a lot of wallpaper paste. Running down the walls in places kind of volumes. I’m assuming that I need to get that off somehow. The paint also peeled in some areas when I removed the wallpaper.

So, any ideas on what I need to do? Is there a wash that will get the paste off, or just elbow grease and hot water. Do I sand/scrape it then? Will I need a primer coat?

Most hardware stores sell trisodium phosphate.
It’s quite good at dissolving old dry wallpaper paste.

If you are painting or re-wallpapering it is best to have a primer on the sheetrock…especially in a bathroom. It acts as a vapor barrier, it helps the paint adhere to the wall, and it allows the paint to dry or cure properly (the paper on the sheetrock wicks moisture out).