What You Will Need
Step 1 - Select the dropdown on the Folder you wish to sync
From the Library page in your account, locate the Folder you want to sync for new content and click on the dropdown menu indicated by the three dots.

Step 2 - Sync the Folder
Click Sync and any new media that should already be in that Folder will now appear.

What You Can Do Now
Auto-Process the Folder for new content
Create a Hub to share the content in the folder