You don't have to use an SSL Certificate but it's recommended. And it's easy: We offer you a free of charge certificate issued by the Let's Encrypt authority.
For a quick test, just use "Preview" mode and everything will work out of the box.
For production setup you don't have to change your setup or send us your existing SSL certificate, with Let's Encrypt you keep full control. If you want to use your existing SSL certificate it must be installed in wao.io 's infrastructure. Please contact our team via chat.