How to use “Auto Add Promo Items for every $X spent” Action
Here is an example of how the “Auto Add Promo Items for every $X spent” action can be used:
Note that in the “Discount Qty Step (Buy X)” field you should state the amount (not a product) that should be spent for the rule to work. You can also set up a condition according to which the $X sum should be spent on particular SKUs or categories.
If you don't want to provide your customers with absolutely free gifts, you can also specify a discount on them using the following settings:
See also: Looking for Magento 2 promo extension? Check out our Free Gift!
See more details on Auto Add Promo Items page