If you are transitioning from the public FHIR API Sandbox (C1941 Domain) to your own Millennium/PowerChart/CPM domain, you WILL need to do the following:
1) Create a System Account (if Build/Cert domains, then typically through https://sandboxcernercentral.com/system-accounts
If Production domains, then through https://cernercentral.com/system-accounts
) -- This creates System Account ID + Client Secret
2) Create new code.cerner.com
SMART on FHIR Apps for each "domain" (This creates App Id + Client ID)
3) Ensure your Launch URL and Redirect URI are configured to the domain/URL/routes on your side where your application is listening for inbound requests.