This option is a good option for people who are new to Facebook ads and/or stores that are just starting to advertise and don't yet have much Facebook Pixel data collected.
When you build your audiences, you have the option to create audiences with the Automatic Lookalike feature.
Creating Lookalike Audiences is usually done by telling Facebook to find people, who are similar to the people who already showed interest in your brand by:
Engaging with your Facebook or Instagram accounts
Viewing your website
Viewing specific product pages
Adding something to their cart
Making a purchase
If your store is new, or has low traffic/conversions, you might not have enough events like purchases or Adds to Cart to build Lookalike audiences from, and you may need to start with something more Top of the Funnel, like Engagement or visits.
The Automatic Lookalike builder automates this decision, by always choosing the source of your Lookalike Audience that is further down the funnel.
When your store doesn't have many conversions or Add to Cart events, Brainity will build the lookalike audience from Engagement or Website visits, but as soon as your store collects more data, it will build Lookalike Audience from Add to cart events, since that would be the audience that is even more interested in your products.