SymptomsButton Create and publish Web site using Sitebuilder is grayed out on the domain configuration page in Plesk Control Panel at Plesk Contorl Panel -> Domains -> your-domain.com -> Setup
CauseClient that owns the domain in Plesk Contorl Panel has Plesk Sitebuidler disabled.
ResolutionYou should enable Sitebuilder for Plesk client that owns the domain first:
Plesk Control Panel -> Clients -> client -> Preferences -> Keep the corresponding user account in Sitebuilder
This makes the button active for the domain.
Plesk Control Panel -> Domains -> your-domain.com -> Setup -> Create and publish Web site using Sitebuilder