I'm a front end developer that has been contracted to redesign a live, custom built, site using concrete5. I cloned all the site files from github, setup a local environment, imported their database dump all as I normally do with every other site I've worked with in the past but when accessing the local site in my browser all I have been getting is a concrete5 branded error message and a link "back to home" which brings up the same error page. It's been several different error messages that I've spent hours parsing through one by one on these forums and im currently stuck on "An unexpected error occurred: Class '\Concrete\Package\CustomizableTwitterFeed\Block\CustomizableTwitterFeed\Controller' not found" and all associated forums on this topic deal with local copies in which other pages of their sites are accessible.

I've never used concrete5 before, I don't have access to the people who originally built the site, and the company who owns the site has never tried to make any changes and doesn't have developers on staff.