curl \
 -X GET https://api.plannrcrm.com/api/v1/document-template/documentTemplate_uuid/content/preview \
 -H "Authorization: Bearer {OAUTH_ACCESS_TOKEN or PERSONAL_ACCESS_TOKEN}" \
 -H "Content-Type: application/json" \
 -H "Accept: application/json" \
 -H "X-PLANNR-ACCOUNT-UUID: {YOUR_PLANNR_ACCOUNT_UUID}"