I replaced _app, admin, admin.php and index.php. I got the following errors:

Warning: require_once(/Users/philippe/Sites/drew_maran/statamic/_app/autoload.php): failed to open stream: Permission denied in /Users/philippe/Sites/drew_maran/statamic/index.php on line 54

Fatal error: require_once(): Failed opening required '/Users/philippe/Sites/drew_maran/statamic/_app/autoload.php' (include_path='.:') in /Users/philippe/Sites/drew_maran/statamic/index.php on line 54

Then I set /_app to 755 which solved the errors. Then I tried to hit the admin panel and I got a 403 Forbidden error:

You don't have permission to access /~philippe/drew_maran/statamic/admin on this server.

Answered by Jack McDade! Go to answer.