Your site is serving a 500 Internal Server Error
.
This can be caused by a number of things, such as:
- File Permissions
- Fatal Code Errors
- Web Server Issues
EDIT
As you have highlighted it is a permission issue. You need to ensure that your files are executable by the web server user
Please see below article for some guidance on proper file permissions.
https://www.digitalocean.com/community/questions/proper-permissions-for-web-server-s-directory