S3 authentication on EC2 with no User and access keys only IAM Role

[coverton-usgs]

I've spun a large EC2 instances using the Rstudio AMI (https://www.louisaslett.com/RStudio_AMI/) my organization doesn't use IAM Users so I don't have an access Key & Secret Access Key to use with flyio_auth().

> flyio_auth() Error in file(con, "r") : cannot open the connection In addition: Warning message: In file(con, "r") : cannot open file '/home/rstudio/.aws/credentials': No such file or directory

But within the EC2 I can access the s3 using aws.s3 commands. Is there any known way to access and open shapefiles without this authentication step?