Is this the process that you had in mind?
You could get this error if the project name has been changed. The default projectName is "/". If you change it you will get "Invalid root node configured for pages."
You could check App_Data\Sitefinity\Configuration\ProjectConfig.config file and projectName attribute. By default the attribute is not added to the config file, so you can try to add it manually. The project name is used as an identifier.
So I assumed this was the wrong way. Which is when I tried going through the startup wizard then copying the config files. This resulted in the previously mentioned error:
Also, on the Primary Key issue - I removed the default templates then refreshed the page, and now it gives the following error:
Just in case it helps anyone to resolve the "The type String cannot be constructed..." error:
At the time of the exception, the container was:
Resolving parameter "providerName" of constructor Telerik.Sitefinity.Modules.Pages.PageManager(System.String providerName, System.String transactionName)
"data source=local\SQLEXPRESS;Integrated Security=SSPI;initial catalog=SiteA_DB"