To see the instructions for using the alternate "Discount code method", see this article.
Simplee Memberships can automatically apply multiple discounts to your member's order. This discounting method doesn't use discount codes at all, but rather we automatically add a discount to the product the shipping in the order.
Not only is this method more simple to configure, it is also more flexible and it also doesn't require the customer to log into their account before moving to the checkout. This method allows members to login during the checkout page and still receive their discount.
Setting up this discount is done during the process of creating or editing a Plan in the app:
Open the "Discount & Free Shipping" section of the plan settings, and choose "Automatic Checkout Discount Method"
Select one or more types of discounts, including Product and Shipping discounts
Choose the amount of discount, the name, and which collections should receive this discount.
If you want to create additional discounts, click "Add Another Discount"
After you save the settings on this page, the discount will start working for members immediately. There is no need to create discount codes in Shopify when using this method.