Great to see this forum.
I am trying to set up a promotion in Magento.
The rule basically is 'If you spent $100 or more, you get product A OR product B for FREE'
Can anyone give me some help with this?
Very much appreciated.
I don't think you'd be able to do this out of the box but one configuration of a promotion rule to try would be to give 100% discount on a product with the condition being that this can only be applied once and if the cart is over $100.
Alternatively, you're more likely to be able to achieve more complex promotions with an extension from the marketplace. For example, this one from Amasty https://marketplace.magento.com/amasty-module-special-promotions-pro.html