The destination path is the location where your new user 'home' folders are. You must ensure that you have created your new users and that each user has their own 'home' folder in this path.
Type the location of the folder into the text area (1) or use the folder button (2) to display a Browse for Folder dialog. You may experience unpredictable behaviour if you select an unsuitable folder!
By default, the finished script will copy your selected content to the 'root' of the user's home path. If you require it to be placed in a sub-folder of the destination home path, you can specify it here (3). Note that the command-line argument preview updates to reflect this change (4).