To clarify, do you already have Quicksight set up in your console, you just want to use it with Quicksight or do you need to start using Quicksight altogether?
The way I know of to do this is to trigger Lambda to create a user, then when you create the template you should be able to assign it a that users email that you, or your end user, has the ability to open. They will get a default email that should start Quicksight for them. You can either hardcode the user email in the CloudFormation template or provide the user email in the parameters.