RTM (Requirement Traceability Matrix):- RTM is a documentation process to cover requirements with creation of test cases like a mapping between business requirements and test cases with functional requirements.
Below is an example but it may be different as per your requirement. This is just an example to design it. It is a very challenging task to cover all business requirements then create mapping with test cases.
In below example:- 1. “User Registration is Business Requirement” with Functional Requirement of Email-Id and Mobile No.
2. “Login is Business Requirement” with Functional Requirement of Login With Email-Id and Login With Mobile No.
*This is an example and more complexity may be there for handling this task so keep practicing with different different examples for learning more*