There are few reasons why you may not able to create a new site, one of the most common reason is that the URL that you are using for creating a new site already exists on the system. May be one of your existing site is using that URL (Domain name) as secondary domain already or it may be linked to a site that you may have deleted. Unfortunately, in order to find if the domain name that is already in use, you would require checking each individual site and if found, delete it from the existing (or deleted) site, in order to use it on the new site.
Another reason can be you do not have enough amount of site. Generally, any Pressero plan comes with a limitation on the number of B2C sites. If you have already utilized the sites that were allotted to you, then you will not be able to create a new site. You would need to either delete one of the existing sites or you may need to contact our salesperson and they will guide you how to get an additional B2C sites.
If you are not able to see any site that has the domain name that you would like to use and if you have sites available to create and are still not able to create a site, then please submit a new support ticket through our Aleyant Support Portal.