Facial Recognition will need to be setup from a browser. You cannot use the smartphone apps to setup Facial Recognition for the first time.
You can use a browser from your smartphone, however there are some limitations. Apple products don't allow use of the camera from the website. Android products do. On either platform you can upload an image, it depends if you are looking to setup facial recognition by taking a photo or uploading one.
Here is a screen shot from using a browser for setup on a smartphone: