Can Bundler automatically add a free product to the order/cart when the customer adds another product from the bundle to the cart?
Bundler can't automatically add products to the cart or to the order when the customer adds another product from the bundle to the cart. It is recommended that you use the bundle widgets so the customer can add all bundle products to the cart with one click.
When the customer buys the correct combination of products (either through the bundle widget or via a default add to cart button on your product pages), the Bundler will apply the bundle discount.
One possible workaround here would be to create a funnel promotion in our Bundler app, in which you promote your bundle. This way, the app can show the whole bundle in a popup when a customer adds one product from the bundle to the cart. This will promote your bundle deal and ask the customer if they want to add the other products to the cart and get the bundle discount.