Cloud Quest: Solution Architect Role.. Cant create serverless database for backup task

Cloud Quest: Solution Architect Role.. Cant create serverless database for backup task.

I try this so many times and I am still getting the same error.. .can someone please help with this one.. the error is below

Your request to create DB cluster database-1-instance-1 didn't work. User: xxx is not authorized to perform: rds:CreateDBSubnetGroup on resource: xxx because no identity-based policy allows the rds:CreateDBSubnetGroup action (Service: AmazonRDS; Status Code: 403; Error Code: AccessDenied; Request ID: xxx; Proxy: null)