I have multiple versions of concrete5 running with different versions of PHP on Dreamhost.
First check which version of PHP you are running (control panel) - 5.6 is recommended.
Second, check if you have an .htaccess file in your install directory, if so rename it and try the install again.
If that still fails, try getting a fresh copy of concrete5 (you didn't state which version), it might be corrupted.
When you start the install, is it passing all the requirement checks?
Is this a fresh install, or are you trying to use a database from another machine?