If you aren't using the internal synth, you must route your vocal (modulator) and your synth (carrier) correctly. In most DAWs, this involves putting the vocoder on the synth track and sidechaining the vocal into it.
TAL provides this version of the plugin as freeware, making professional-grade vocoding accessible to everyone. Tips for Using TAL-Vocoder in Your Tracks tal vocoder download
The interface is clean and avoids the "option paralysis" found in more complex plugins. If you aren't using the internal synth, you
Optimized for live performance and real-time studio monitoring. How to Download and Install TAL-Vocoder tal vocoder download
The download usually comes in a compressed .zip folder. Extract the plugin file to your system's VST or Component folder.
Navigate to the Togu Audio Line (TAL) downloads page.