Execute this command in your terminal

composer require fjerbi/ultimate-admin-bundle

Add these lines in your services.yaml

 fjerbi\AdminBundle\Controller\AdminController:
        calls:
            - method: setContainer
              arguments: [ '@service_container' ]

Add this in your routes.yaml

admin:
  resource: '@Admin/Controller/'
  type: annotation
  prefix: /admin 
  

And finally execute this command

php bin/console doctrine:schema:update --force

check your database if the new tables were added successfully

NOTES: if you want to check the routes just execute this command

php bin/console debug:router

What's included ?