at a glance answer.
…instead of
rails generate devise:views User
use:
rails generate devise:views
If you’ve already done it, move the folders devise created from app/views/User to a new folder app/views/devise (or just rename the User folder to devise, if that’s an option.)
Those folders are:
app/views/User/confirmations
app/views/User/mailer
app/views/User/passwords
app/views/User/registrations
app/views/User/sessions
app/views/User/shared
app/views/User/unlocks
No other changes are necessary.