Hi,
By default, this link goes to the Learnpress login page. If this is not working please download the theme again and upload it from Appearance -> Themes -> Add New. As the theme is already installed on your WordPress it will ask you to update and replace. Click on the updated and replace option.
Now go to Appearance => Customize -> Theme Settings -> Top Bar. Put the link you want in the Add Login button URL and then check.
Please try and let us know.
Thanks