Authentication is passed via bearer token. This is done via taking your institution's API key passing it in the Authorization HTTP Header in this format:
Authorization: Bearer <api_key>
Ways to pass authorization headers
In browser, via an extension that modifies requests (e.g. Postman)
Terminal usage: via curl(1) or wget(1) (see examples)
Programmatically via network requests (see examples)
You can access https://app.eduflow.com/api/graphql and Login as an institution owner / admin to access graphiql directly. To see this in action see the graphiql usage example.