Currently you can only create a repeat task on the web-app and not on the mobile app.
Click the "Repeat Task" button once you set the due date of the first task.
From the top "+ Task" button
From the task list
From the "Plan" sidebar
Set Repeat Pattern
Example: Every Week On Wednesday
Set When Task Stops Repeating
Copy Attributes of The First Task to The Following Tasks
Confirm (Set Dates)
Check Dates and Edit Repeat Tasks if Necessary