How to store / add (third-party) API Credentials

Describe the problem/error/question

What is the best way to securely store API credentials, would that be via variables? https://nylas.app.n8n.cloud/variables

What is the error message (if any)?

N/A

Please share your workflow

Working on an email automation workflow using Nylas Email API.
https://nylas.app.n8n.cloud/workflow/rezwNjEv2XQbzYPX

It sounds like you need an external secrets store?