Hello @ifaiyazhossain ,
Welcome to the MS Q&A forum.
My apologizes for the delayed response. Regardless your question is being asked the long time ago, I am posting my answer in case if someone else will come around your post while have the same or similar questions regarding assigning roles in the Azure.
Azure role-based access control (Azure RBAC) is the authorization system you use to manage access to Azure resources. To grant access, you assign roles to users, groups, service principals, or managed identities at a particular scope. This article describes how to assign roles using the Azure portal.
If you need to assign administrator roles in Azure Active Directory, see Assign Azure AD roles to users.
Sincerely,
Olga Os