The Solo plan is set up for a single person. It allows you to have one saved signature. While you can continue to edit the signature and you could swap out employee names and contact information, this means it leaves you to do the work of personalizing everyone's email signature. With the Starter and Pro plans you have the ability to make one template, define which fields are customizable, and then simply send your client a link where each employee can fill in their own name and contact details. This removes the production work from you and allows you to focus on design.