Vault
To use your Vault installation you need to unseal it after each restart. For this you need at least three of the five unseal keys.
The keys will not be stored inside the app. You can initialise the vault after install by going to the URL where the app was installed. Following directions from there. After download store them in a safe place or distribute them among trusted entities.
Docs can be found here https://learn.hashicorp.com/vault/getting-started/deploy