The launch template requests Spot instances with at least 1 vCPU and 1GiB of memory up to 4x that. This will often select the "best value" instances which are capable of running the work, but not wasteful.
The cloud-config is embedded within the launch template, base64 encoded, sets up K3s, and applies my manifest (my user-name is embedded, so you probably want to replace https://cdn.n0t.dev/public/aws-spot.yaml
with something of your own). Additionally, it installs stern which is just a handy way to get logs out of the cluster.
You'll need to do the AWS basics such as creating a keypair and configuring your security group to allow SSH in order to access your instance. But once on it, you can:
Login to your instance:
chmod 0600 ~/your-aws-key.pem
ssh -i ~/your-aws-key.pem ubuntu@127.0.0.1