Calendly's API v2 at https://api.calendly.com identifies users and organizations by URI; most list calls take one of those URIs as a filter.
Create a token at Integrations → API & Webhooks. Send it as Authorization: Bearer <token>. In the examples it's written {{CALENDLY_TOKEN}}.
Full reference: https://developer.calendly.com/api-docs
Returns your uri and current_organization.
curl https://api.calendly.com/users/me \
-H "Authorization: Bearer {{CALENDLY_TOKEN}}"
user is your URI from the call above.
curl "https://api.calendly.com/scheduled_events?user={{USER_URI}}&count=10" \
-H "Authorization: Bearer {{CALENDLY_TOKEN}}"