Have a look at this little quick start manual to get started using the Emy 2019 speech synthesizer. The 2019 version comes with a generic panel that simplifies using an add-on hardware speech synthesizer.
It describes how the interface is designed in 2 majors sections.
The left side of the panel is dedicated to choosing what to say while the right side allows tweaking the voice or the sound being produced.
It also describes the various software options.