Copying is available to paid users only as there's a limit of 1 CJM, 1 impact map, and 1 persona per user on the free plan. So, if you're the one with a paid plan:
Open up the project with the map you want to copy.
Click on the COPY icon on the right of the map’s bar.
You’ll see a popup window where you can choose a target workspace and project.
To copy a CJM together with maps and personas that are linked to it, check the box near the “Copy all linked map/personas” option before confirming the copy action. To copy a CJM structure only, select the "Clear all content" option.
Copying CJMs in Bulk
To copy CJMs in bulk, check the boxes near them and hit COPY on the action bar.