When I go to the setup page my browser tries to download a file

If your browser tries to download a file rather than displaying the setup screen when you visit perch/setup the most likely problem is that your server is not running PHP or PHP is not configured properly.

If you should have PHP running then contact your hosting company for support. The Perch compatibility test suite should indicate any problems with PHP. If the test script runs correctly but you still have a problem with the setup page please open a ticket here and we will help you to get started.