Problem Requesting OAuth2 Access Token for HubSpot API - CORS-related?

I’m having trouble using Postman to request an OAuth2 access token (from HubSpot for their API). In my Collection I’ve gone to Authorization, chosen OAuth2, and clicked “Get New Access Token.” I filled in the (hopefully) appropriate values in the popup, and then clicked “Request Token.” It brings up the page to log into HubSpot, but when I click “Log In” the page says “There was a problem logging you in.”

When I look in the JavaScript console, I see the following:

Does that part about no “Access-Control-Allow-Origin” indicate something about CORS?

If I take the URL that Postman is posting to and paste it into my browser, it works - can log into HubSpot and get redirected to my redirect URL with the code in it - so something is different in Postman.

I’m using the native app v7.3.5 on Windows 10.

Thanks for any help!