YITH WooCommerce Wishlist is a plugin where your customers can add products they are interested in to one or more wish lists. This process allows them to check these products back again at a later time and eventually proceed to purchase them.
The integration between these two plugins allows showing the “Add to Wishlist” button in the “Save for Later” list.
To do it, you need to install and activate both plugins, then go to YITH > Save Cart for Buy later > Settings and enable the option Show “Add to Wishlist”.

Once enabled, users will the the “Add to wishlist” button in the list:

To read more information about how to configure YITH Wishlist, you can check the full plugin documentation here.