The reason why it returned "No code parameter" is due to the prompt parameter value set in OpenID configuration. Setting prompt parameter with the value 'none' means that there is no active session from Identity Provider side (the End-User is not already Authenticated in Okta) to authenticate silently.
<auth-request-prompt-value>none</auth-request-prompt-value>
If you want to use the 'none' parameter then you should ensure to establish the session in Okta and then login with Spotfire. If not, you can change the parameter to 'login' so that the Spotfire Server attempts to Authenticate the End-User even if the End-User is already authenticated.
<auth-request-prompt-value>login</auth-request-prompt-value>