Hi mate I'm a little confused. If your item is not free it won't be included, and will show the normal add to cart button. What setting have you selected on the memberships settings page in my plugin settings?

Exclude membership restricted items

Include paid items that have 100% discounts for members.

Not logged in can be prompted properly

But ordinary members can download unlimitedly.

You need to select the first option to include membership restricted items. That means members who are eligible to purchase a restricted product, and it's free, will be able to download it.

The problem has been solved. Thank you.

Great to hear! 🙂