Service API Setup

Hello,

Hopefully an easy one here. I'm new to Service API and am trying to setup the service according to the docs:
https://docs.developers.optimizely.com/customized-commerce/v1.3.0-service-api-developer-guide/docs/installation-and-configuration

I have added the following code to the Startup class:

services.AddOpenIDConnect<SiteUser>(
    useDevelopmentCertificate: true,
    signingCertificate: null,
    encryptionCertificate: null,
    createSchema: true,
    options =>
    {
        //options.RequireHttps = !_webHostingEnvironment.IsDevelopment();
        var application = new OpenIDConnectApplication
        {
            ClientId = "postman-client",
            ClientSecret = "postman",
            Scopes = { ServiceApiOptionsDefaults.Scope }
        };
        // Using Postman for testing purpose.
        // The authorization code is sent to postman after successful authentication.
        application.RedirectUris.Add(new Uri("https://oauth.pstmn.io/v1/callback"));
        options.Applications.Add(application);
    },
    configureSqlServerOptions: null);
services.AddServiceApiAuthorization(OpenIDConnectOptionsDefaults.AuthenticationScheme);

But upon starting the application I simply get an ArgumentNullException "Value cannot be null. (Parameter 'connectionString')"

Is the documentation still up to date here? What am I missing?

Regards, Stephen