With a small team, I'm using an open source tool called reqflow (https://goeb.github.io/reqflow/) to track requirement to source code with a Doxygen keyword //! \ref RQ-xxxx. It's generating a traceability matrix and is quite simple to use (perfect for a small team). In my case, I'm using grep on the source code to create the traceability matrix.

For tracking requirement to test, I'm using testlink (testlink.org) where you can enter your requirements from existing documents and linked them to test cases. The documentation is not perfect, better start here:

https://www.guru99.com/testlink-tutorial-complete-guide.html

You can go to Bitnami to get a docker image.