Text-to-speech is outside this editor
The current audio editor does not synthesize spoken audio from text. No registration, activation or paid upgrade adds that absent function.
Prepare a narration separately
Record your own narration with the separate recording application, or prepare an accessible audio file with a separate speech tool of your choice.
Edit the resulting audio file
Open the local narration file in the waveform editor to trim, join or apply supported effects. Export a new copy and keep the source recording.
The current Windows product directory lists the supported free applications. It does not offer an installer for this absent product or function.