Miro's REST API v2 lives at https://api.miro.com/v2.
Create a token at your Miro app's settings (install it to your team). Send it as Authorization: Bearer <token>. In the examples it's written {{MIRO_TOKEN}}.
Full reference: https://developers.miro.com/reference/api-reference
curl "https://api.miro.com/v2/boards?limit=10" \
-H "Authorization: Bearer {{MIRO_TOKEN}}"
curl -X POST https://api.miro.com/v2/boards/{{BOARD_ID}}/sticky_notes \
-H "Authorization: Bearer {{MIRO_TOKEN}}" \
-H "Content-Type: application/json" \
-d '{"data": {"content": "Created from PostTaco"}}'