Multi-Factor Fails To Enable On Directory Service For DUO/VPN setup

Hey there, been having trouble trying to enable Multi-Factor for Directory service in order to integrate DUO with my VPN client. I have followed to the post here to a tee but when I go to enable MFA it keeps failing: https://aws.amazon.com/blogs/networking-and-content-delivery/using-microsoft-active-directory-mfa-with-aws-client-vpn/

So I have everything checked off. I do have an EC2 instance joined to the domain. I have rules in place that allow the radius port through. I have also tested connectivity to the EC2 instance from Directory service and it reaches it fine. I have my config for DUO setup according the post above, matching DUO keys and verified the shared radius key is good. But with that being said, its not very clear on the EC2 instance should have radius /NPS role installed and configured. It only mentions having a radius server. So just to see, I did install the NPS role and set it up for Directory service as a client. When trying to re-enable MFA, I do see DS trying to connect and creates an error in the log. Event ID:6273 Network Policy Server denied access to a user.

Contact the Network Policy Server administrator for more information.

User: Security ID:NULL SID Account Name:fakeusername Account Domain:MYDOMAIN Fully Qualified Account Name:MYDOMAIN\fakeusername

And just to note, the "fakeusername" is actually what is appearing in the log. Now there is no area in the whole setup where you create a system account or some account for DS to connect to radius server so I am bit puzzled in this. Obviously, there is not user by that name and for fun I did create one with the radius secret just to see if that would do anything but of course it still fails. If there is anyone that help provide any insight to this, I would appreciate your time. Thanks! Chris.