You already have a WordPress installation with a domain name mydomain.com and you want to add a sub-domain, for example shop.mydomain.com.
Here's how to achieve that:
Using the Pressidium Dashboard
Select the Websites menu option from the Dashboard sidebar.
Click on your website's name to go to the website overview.
Click Domains to view all the domains associated with the website.
Click Add to navigate to the New domain name screen.
On Step 1 enter the sub-domain (e.g. shop.mydomain.com)
On Step 2 ensure that you have setup / configured the proper DNS records for the sub-domain you are adding.
On Step 3 select see the website directly to have visitors see the website immediately or a redirect option.
On Step 4 select whether to enable SSL or not. You can opt to use a free Let's Encrypt certificate, automatically generated by our platform or a custom one uploaded by you. Note: If you select to use a Let's Encrypt certificate you should ensure that DNS records are properly set or the certificate issuing process might fail.
Click Submit to add the sub-domain. You can monitor the progress using the Activity in Progress sidebar panel and a Dashboard notification will be displayed as soon as the provisioning process is completed.