Zephyr Enterprise doesn't appear to let you map requirements to the test cases at the Project Test Repository level. They can only be mapped once you have created the Release Test Repository(ies) and moved the Requirements into their relevant Release Requirements folder.
I don't really understand why this is the case. Wouldn't it make sense to allow all PROJECT requirements to be mapped to any PROJECT test cases up front as a one-off exercise? Once all your project requirements have been mapped to test cases in the Project test repository, it would simply be a matter of creating your release test repositories and moving the relevant test cases into them. ##The requirement mapping from the PROJECT level would need to be automatically retained across any subsequent RELEASE(s) where a mapped test case is going to be executed in order for this to work##
This strikes me as a much more efficient option to have available, rather than having to manually move and map a requirement in each Release where its corresponding test case(s) are executed which seems unnecessarily labour intensive.
I note that the option to 'Map Test Cases' is displayed (but disabled) in requirements at the project level, so I wonder if this functionality used to be available? In which case, can we have it back please?