To load it form S3 folder you need to specify path with s3 scheme in the following format: s3://[region]@[bucket-name]/[file-key].
The region is optional but recommended.
You don't need to provide AWS credentials explicitly. You can use the default AWS credentials chain. Or you can use shared credentials (in ~/.aws/credentials file).
The simplest way is to assign an AWS IAM role to your machine instance or export env variables.
Here is an example of running the identifo with a s3 config.