If testers are not getting requirements in a way that it is usable to create requirement traceability matrix, and assuming that they have the time, I recommend taking the knowledge of the system that they have and writing their own test requirement matrix. These kinds of matrix should be used internally for traceability. This method has worked for me in the past.
The best outcome was that, as the word of these requirement matrix got out to other groups in the company, they began to see the value of them and made our testing efforts more efficient and they wanted to see what it could do for them, resulting in requirements adoption.