After having created and configured the IpPbxExtionsions database the table which is used by the PersistentVariable GSE action needs to be created into this database.
Select Open | Open File... from the File menu of SQL Server Management Studio and select the file CreateTable.sql from the sql folder of the download package.
Note: if you have chosen another than the default name for the database in the previous installation step you need to modify the first line of the CreateTable.sql file accordingly.
Click Execute from the toolbar. Afterwards right click IpPbxExtensions in the tree view and select Refresh. Open the IpPbxExtensions and Table branches to check if the new table dbo.PersistentVariables was created.
The database is now fully created and configured !