The diyHUE documentation mentions in the "Registering the remote in Hue app" section :
This will register the remote in diyHue and it will pop up in Hue app, in Accessories section.
It should be
This will register the remote in diyHue and it will pop up in the Philips Hue app, under Settings > Accesory setup, or under Devices > Smart Controls in the Hue Essentials app.
The diyHUE documentation mentions in the "Registering the remote in Hue app" section :
It should be