adding soil would probably be good along with some organic fertilizer

I agree with randy that you need soil mixed with the compost. I'm also highly skeptical of using municipal compost especially in an edible bed. A lot of the general public and small contractors will put all sorts of stuff in their city compost container not to mention accidentally mixing things in that should never go into compost.

Do grow a bean in it first, just to make sure there were no lawn clippings contaminated with herbicides!

There could be things in it that inhibit plant growth, particularly some long lasting herbicides and then other toxins that should not be dumped out at all, but people do . . . so frustrating. We got some great compost from our local municipality as far as how it looked, but it just isn't as great as it could and should be due to the limitations of what municipalities can do as far as control what gets dumped . . .Of course this is a generalization. Check with the folks managing the facility to see if they do any monitoring of what gets dumped. There are places that do a good job.