Create a Schedule Line on release of production order

We would like create automatic schedule lines based on Release of Production Orders.

We are getting requsitions, but not sure as how to proceed with those requesitions to do a GR

Have maintained ME31l, but left the ME38 / ME84 empty

In routing - Maintained the external operation with Outline agreement #.

Res/ Pur Req = 3 setting

and it generates a purchase requsition!

Is the Purchase requsition needs to be converted into schedule lines?

ME59 is not picking them up.

Any help be appreciated.