In on-premises environment, client registration depends on the identity provider.
Smart Completions Authentication identity provider
Client registration is not required when using the Smart Completions Authentication identity provider in the on-premises installation environment.
The Smart Completions Authentication identity provider supports only the basic authentication grant type, which does not require client registration.
Azure AD identity provider
Client registration is required when using Azure AD as the identity provider in an on-premises installation environment.
Contact your Azure AD administrator or see the Azure AD help. Upon successful registration, your Azure AD administrator or Smart Completions administrator will have access to the authorization details needed authorize requests.
To keep your company and customer data safe, do not share this information with anyone! This information will allow anyone to access your data, and that access might not be limited to only data stored in Smart Completions.