Corda on AWS using quickstart guide

Hi all. I’m trying to deploy corda nodes in new VPC on AWS using the following: Corda on AWS - Quick Start
But I’m running into this error: Cannot find version 9.6.9 for aurora-postgresql (Service: AmazonRDS; Status Code: 400; Error Code: InvalidParameterCombination

Is this error expected? I didnt make any changes to the CF template yet still running into this issue. Any help is appreciated.