Hi Cliff,
What you need to do is enable our “Products” section (in “WooCommerce > Settings > Order Min/Max Amount > Products”), and add your charity product to “Individual Products > Exclude” there. Also, please make sure that the “Validate all products” checkbox is disabled there – when your customer adds both charity and non-charity products to the cart – this will ensure that min amount will be applied again.
You may also want to enable our “Cart Total” section, and add your charity product to “Individual Products > Exclude” there as well. This will matter if your customer will add both charity and non-charity products to the cart – do you want the charity product to be added to the cart total or not.
Hope that helps. Please let me know if you have any questions.