rails active_storage:install IS NOT WORKING

Your problem is here:

require "active_storage"

You need to require the engine:

require "active_storage/engine"

The current rails official documents talks about the new application. But if you're upgrading a pre 5.2 app, you have to add or uncomment the field in application.rb

require "active_storage/engine"

For the new application, this will be already added.