So in case you are using a self-hosted installation of Post Affiliate Pro (or Post Affiliate Network) you have to ask your server administrator (or hosting administrator) to install an SSL certificate for your server.
Every paid hosted account of Post Affiliate Pro works also with https:// out of the box.
In case you wish to park a custom domain on your hosted account of Post Affiliate Pro and access it via secure connection, you will have to use your own certificate again (not the wildcard one). Please, refer to the following guide:
HTTPS redirect for merchant or affiliate panel