We are actively building a feature that will allow you to connect a Telerik Backend Services project to an existing database (MS SQL, Oracle, etc.). It is planned to be delivered soon. We are currently assessing the performance and reception of several scenarios. The use cases that you have described are among them, but currently we cannot announce the final specifications of this feature.
Telerik Backend Services offer out-of-the-box methods for user management with AD FS authentication
. In the case of WAAD, this authentication is supported with passive federation and will be available only in web and hybrid mobile applications.
Telerik Backend Services are built and running on a MongoDB database.
Let us know if any further questions arise.