Single account
Use this path if CloudShell, CloudFormation, and Terraform aren't viable in your environment. Those automated options are faster and less error-prone — the wizard generates a ready-to-run script/template for each.
AWS Organization
Use this path only if CloudFormation StackSets and Terraform aren't viable. For organizations with more than about five member accounts, use CloudFormation or Terraform — they roll out the role to every member automatically and keep it up-to-date as new accounts are added.