Log into your Snapchat Ads Manager account.
Click the menu at the upper-left corner and select "Catalogs". You will see two options: "Manually Add Products" and "Use Product Feed".
Click "Use Product Feed".
Name your catalog.
Input your feed URL.
Indicate the time of day you would like Snap to refresh your catalog.
Wait for the product catalog to be imported, it may take about 10-30 minutes.