It is possible to connect to Web traffic data in your new GA4 account but you need to enable it first in the Google Analytics 4 property.
When setting up your Google Analytics 4 property you need to select "Show Advanced Options" and turn on "Create a Universal Analytics property" switch. Click Next to complete this setup. After you have done this, you will be able to see your Web Property in Octoboard when connecting to your GA4 account.
Google Analytics 4 is a new development from Google and it does not yet have a specific API to retrieve combined views for Web and App analytics. We will of course support it as soon as the feature becomes available from Google.