Facebook Business Manager is the recommended platform for managing all your Facebook ads. There are certain features (such as catalog-based retargeting ads, or DPA's) that are only available in ad accounts that are managed through Business Manager.
It's very easy to sign up for Business Manager. After you create the Business Manager account, you can "claim" your personal account so that you can manage it through the Business Manager. At that point, you can take full advantage of the features and protection that the Business Manager gives your ads.
Sign up for Business Manager on Facebook here: https://business.facebook.com/
Please note: If you do not set up a Business Manager to use with Win Ads and your Facebook Ads, you will not be able to use the Facebook Catalog and Feed functions in Win Ads. Facebook Catalogs reside in Business Managers. Therefore, they cannot be created without a Business Manager.