Adding a cluster to rancher when I dont have aws keys, only an ec2 instance role

Hi, I am in an environment that is somewhat locked down and the customer will provide AWS keys. I have used terraform to spin up a rancher instance in govcloud but I want to add another cluster under it using the UI, but it is asking me for AWS ACCESS ID and Secret Key but all i have is the IAM Instance role attached to the ec2 instances for the rancher server and the cluster nodes.

Does anyone know how to get around this? any insight or discussion appreciated.