No. There are no magic folders or any type of action for you to make sure your files are included. 

By default, younity will automatically scan your entire hard drive at  Users/your username.  If you would like younity to share specific folders and files to your mobile devices you have ability to change the location.   

Here are the instructions to do so .

1 After installing younity, start the registration process by creating an account

2 Once registered, click the younity symbol in your OS bar

3 Click “Preferences”

4 In the “Location” tab, highlight your hard drive, click “Remove Selected Location”, and then click “Save

5 In the same tab, click “Add Location”, and then click "Save Changes" .