The Register link on the WishList Member Widget (often referred to as the Login Widget) directs to the Non-Members page.
The Non-Members page is where users will get directed to if they do not have access to the area they are attempting to view.
The thought behind having the Register link direct to the Non-Members page is that a Non-Members page typically includes the option to register.
Providing the option for users to register on the Non-Members page is useful since they were just redirected after wanting to access a piece of protected content they cannot view.
Also, your site may have multiple Levels. So by including that Register link on the WishList Member (Login) Widget directing to the Non-Members page, you could then display multiple links to multiple registration forms.
Please note, if your Home page is appearing when the Register link is clicked, that is likely because the default Non-Members page is the Home page if one hasn’t been set.
You can set the Non-Members page in the Advanced Options > Global Defaults > Error Page section of WishList Member.
There is also an option to remove the Register link from the WishList Member (Login) Widget.
This can be done in the Appearance > Widgets section of WordPress.
You can click the box that allows the Register link to be shown or not in the WishList Member Widget settings.