When you created a Scheduler on Azure on current version, your default scheduler will not be the free one, it is a standard package, which needs you pay money.
I did not realized it until I was charged. and I reviewed the creating steps, I found these was a message which was in a gray background when I created Job Collection, which is not easy to see (why? Microsoft).
So where is the Scale tab ?
You have to create a Job Collection first, then change its scale, like below:
But you have to know when you switch to Free plan, the max recurrence will be up to 1 hour once time, you can not set any of your job less than this frequency.
Updated: Azure Scheduler is going to be replaced by Azure Logic Apps. Check here.