AD Security Group Not Found in Power BI: Embed Power BI

I'm currently facing difficulties in generating the embed token. My plan is to implement Row-Level Security (RLS) so that different users can only view their respective information on the Power BI dashboard that I am embedding.

I understand that the embed token is generated from the access token, and this access token is generated in different ways depending on how you want to authenticate. Following some topics in the Microsoft documentation, I adopted this model: https://learn.microsoft.com/en-us/power-bi/developer/embedded/embed-service-principal

I've already created the application in Azure and the client secret, thus obtaining the service principal. With this, I managed to generate the access token using the POST method on the API https://login.microsoftonline.com/{tenantID}/oauth2/token. I've also created a security group and added the application as a member.

However, when I attempt to enable the service principals to use Power BI APIs for the specific security group, I encounter the error 'You cannot use invalid or duplicate emails.' This occurs during the second step of stage 3, as outlined in the documentation mentioned in the link above.

I've tried using the security group's ID, the security group's name, the application's ID, and the application's name, but none of them can be located in the Power BI service administration.
I found a similar post here: https://community.fabric.microsoft.com/t5/Service/Adding-AD-security-groups-to-PowerBI-app-workspace/m-p/651836, but I would like more details on what might be missing from the AD side, as it mentions synchronization only.