Fortigate 2fa for RD Gateway

I want to setup the 2fa in the Fortigate to protect a RD Gateway and OWA behind the Fortigate with Radius.

The Radius is working, but when I add the user to the  RD Gateway policy the 2fa is not working and the gateway is not reachable.

 What I did so far:

1. Added the WIndows Radius server to the fortigate

2. Adder a user with Radius and enabled 2fa with e-mail

3. Added the app on my phone and registered the token

4. Enabled push notification for 2fa

5. Added the user to the RD Gateway policy Source User

Is what I want possible with the fortigate?