To install ChatNet you have to access the install page via yourdomain.com/install
If you are getting an 404 error when you hit the yourdomain.com/install URL, it could be due to one of few of the following issues.
If you can not find the .htaccess files, It is in the downloaded zip file from Codecanyon. Allow hidden files to be visible on your PC or Mac. Sometimes Windows and Mac OS hides .htaccess files.