Hi Claudio
In order to fix this issue, you will need to configure the NameID to the email address on the IDP side as NameID is mapped to the email address and username in the plugin. Can you please let me know what is your IDP so that I can assist you further?
You can also reach out to us from the support forum given in the plugin dashboard so that we can get on the call and help you set up the plugin end to end. We can also help you debug the issue on IDP side.
I would also like to mention that in the paid versions of our plugin, you can set the email and username at WordPress to any attributes sent by your SAML IDP, not just NameID.
Thanks,
Krishna
