Creating a Recurring Payment during initial sale
The action code "makeRecurring" can only be used in conjunction with the “captureToo” flag set to “yes.” allowing you to create a recurring transaction during the initial sale request. which will create a recurring payment when the initial payment is approved.

For testing set the following fields after selecting the "Try It" button
externalReferenceID = Unique record identifier for processing - you assign Numeric Min = 16 Max 19
transactionDate = Set to UTC timezone, Format 2020-08-25T17:01:01

Click Try It! to start a request and see the response here!