Deskpro support SSL/HTTPS connections in order to allow for secure connection to the helpdesk for your agents and users. This is setup within your webserver configuration. You can opt to order an SSL from a provider, or make use of Let's Encrypt which is a free certificate authority.
For SSL to work, you should make sure the PHP OpenSSL extension is installed (you can check this from Admin > Server > Server Requirements). This will automatically be installed if you use our VM templates or our one-line installation script.
You should also set the Helpdesk URL in Setup > Settings to the point to the https:// version of your domain name.