Once you have created a new map you will need to create a project.
If you have data in the Boundaries section, such as Land Registry or RPA data click on the 3 vertical dots to the right of the data.
From the menu select duplicate.
The duplicate project menu will appear.
Select the project type you would like to use, input your new project name then select create project.
Your new project will now appear under projects and your duplicated data will show on the map.
Now the data is in a project you will be able to edit the data.