Add Products is exclusively utilized for adding products to campaigns.
When using Add Products in Sales & Orders, the app will structure a given campaign automatically, thus eliminating the need for grouping products together:
No Product Groups: Because products are not grouped together, each individual SKU will be built as its own line item in your campaign and ad group(s)
Products Per Ad Group: A maximum of 14,000 products will be allotted to a single ad group in a given campaign. S&O will automatically build the number of ad groups required to support your total product count
Just like in Update Bids, Add Products allows you to use filters to manage your product adding:
By default, Add Products filters automatically by Source = Approved and Pending products only.
Disapproved products in Merchant Center will not be eligible for ads so they are initially filtered out from adding.
From the Filters panel, you can adjust your criteria based on your specific needs.