How to configure AWS VPN with Federated authentication on Android?

I have an AWS Client VPN that I use successfully in my laptop. Nonetheless I've not been able to configure it on my Android phone. The issue is, I think, that this VPN uses federated authentication (with Microsoft's Active Directory), and the OpenVPN Android client doesn't know how to use it. From my laptop, using the AWS VPN Client it opens a web browser that authenticates against Microsoft each time that I connect to the VPN, but on Android this browser window is not being opened. Does anybody know how to set this up? This is what my AWS VPN client file looks like:

client
dev tun
proto udp
remote hello.cvpn-endpoint-REDACTED.clientvpn.us-west-2.amazonaws.com 443
remote-random-hostname
resolv-retry infinite
nobind
remote-cert-tls server
cipher AES-256-GCM
verb 3

-----BEGIN CERTIFICATE-----
REDACTED
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
REDACTED
-----END CERTIFICATE-----

-----BEGIN CERTIFICATE-----
REDACTED
-----END CERTIFICATE-----


auth-user-pass
auth-federate
auth-retry interact
auth-nocache
reneg-sec 0

Notice that: - My endpoint says hello as I found out the OpenVPN app doesn't honour remote-random-hostname to prepend the random string to the url (used to bypass DNS caching), so I had to add a random string manually. - The config file says auth-user-pass but I don't have a username and password for the VPN, besides the one from Active Directory, which I've already tried with no luck.