Thanks for your interest in Alces Flight!
Generally for most use cases we recommend launching an Alces Flight Compute cluster using our Cloud Formation template rather than launching individual instances, as this is intended for situations where only a single Alces Flight node is needed. Using the Alces Flight Compute Cloud Formation template provides you with an already configured, auto-scalable, and secure cluster, without you needing to further configure this, which works best for most use cases.
You can launch an Alces Flight Compute cluster using the Cloud Formation template by selecting the "Personal HPC compute cluster" rather than "Single AMI" option when on the Alces Flight page in the AWS marketplace.
Hope this helps, let us know if you need any further assistance with Alces Flight.