I don't think that sidekiq-pro offers recurring jobs.
For terminology sake, a scheduled job would be the result of an action telling the background processor to schedule the job for a later time. For example, if a new user signs up for your application, you can set a scheduled job to thank the user for signing up and give some tips about your application 24 hours after they sign up.
A recurring job or periodic task, would be something where you are wanting to perform a task every x intervals. For example, if you have a ToDo list application and you want to send a notification to your users every morning with an overview of what they still need to do or have completed the previous day, sidekiq-cron would be a good fit for the job.
You should be able to use sidekiq-cron along side sidekiq-pro. However, if you're using sidekiq-enterprise, there is no need for sidekiq-cron since this functionality is built into sidekiq-enterprise.