As the documentation says: File -> Save configuration creates a ZIP archive with all your Actions (and settings and more).
Mp3tag does not have a File -> Restore function.
You will need to manually copy the saved configuration ZIP archive to your new computer and manually extract it into the folder where you installed Mp3tag.
If you only want to restore your Actions, extract only the contents of the \data\actions folder from your ZIP archive.
Mp3tag helps you to locate the correct target folder with File -> Open configuration folder