In the system.webServer/httpProtocol node in the DNN web.config, add the following custom headers. If your local development host differs from localhost:4200, change the value accordingly.

<customHeaders>
    <add name="Access-Control-Allow-Credentials" value="true" />
    <add name="Access-Control-Allow-Origin" value="http://localhost:4200" />
    <add name="Access-Control-Allow-Headers" value="tabid,requestverificationtoken,moduleid,contentblockid" />
</customHeaders>