Hello,

While installing this program by following the instruction readme file, I found one more step should be done.
I resolved this issue, but I just posted to let you know.

When setting the instance manager VM, the IAM policy should be added.

In the AWS console,
IAM > Policies > Create policy >

1. add service EC2 and select actions; "DescribeImages", "TerminateInstances", "RequestSpotInstances", "CreateTags", "RunInstances", "DescribeSubnets", and "DescribeInstanceStatus"
2. add service IAM and select actions; "CreateServiceLinkedRole", "ListRoles", and "ListInstanceProfiles"

After creating the policy, go to the created policy and click Entities attached.
Then, attach the IAM User created before.

I could successfully run python3 api.py input-args-wireguard.json simple-test in instance_manager_setup.md after this setting up.