Error configuring S3 Backend: no valid credential sources for S3 Backend found

I have an OCI Instance and trying to run terraform plan on a folder(checked out from repo) when I run the terraform init it gives me this error.

Initializing the backend…
Initializing modules…

│ Error: error configuring S3 Backend: no valid credential sources for S3 Backend found.

│ Please see Backend Type: s3 | Terraform | HashiCorp Developer
│ for more information about providing credentials.

│ Error: NoCredentialProviders: no valid providers in chain. Deprecated.
│ For verbose messaging see aws.Config.CredentialsChainVerboseErrors


But how do we need to provide access and secret keys when running terraform as instance type auth? Also I am running on existing repo and I want to run only terraform plan

Any help would be highly appreciated