Can users log into a protected category by clicking on a link?
The Password Protected Categories plugin comes with 3 types of protection: password , user and role protection. You can only log into a password protected category by manually entering a password on the category page or a central login page. However, user and role protected categories work with WordPress user accounts, which gives you more flexibility.
If you want to let people click on a link to automatically unlock a protected category, then you can do this by using user or role protected categories with a free plugin like Magic Login or Login Me Now. This lets customers log into their WP or WooCommerce account simply by clicking on a link to a secret login URL. It then logs them into their account automatically without having to enter a username or password.