Assigning users to only specific pages – is this possible?

I am not sure if this is the right place to post this question. If it isn’t, let me know.

A group of businessmen want me to re-design their site. The site is https://www.garrisonmn.com. The site is broken down by business type and then each business has their own page. I originally said a word press blog would work well for them. But now each business wants to be able to go in and update their own page.

Is this possible? I thought I read there was a plug-in, but that it didn’t always work.

Or is there a better way to go here?

Any input would be appreciated. Thanks.