Hm, i tried to install on localhost, i limited to 1000 bytes and no error appeared, forum works
I also checked the integrity of the files and found that 200 files were missing in the core of the forum (/core/install/, /core/includes/ and /includes/ folders)
So… could you try to upload those missing files?
The bulk file uploader in the file manager is unreliable. By far the most reliable method to upload a full website is to use a desktop FTP client like FileZilla.