Basically, it does nothing. I think that it didn't install the voices because the select combo is blank. I am on Firefox – Arch Linux – Kernel 6.1.12 – x86_64.

Não percam seus tempos baixando essa atrocidade, não inicia, e nem sequer funciona corretamente, visto que nem as leituras de texto ele executa, mesmo estando com o modo anonimo ativado.

SPYWARE! Look at the permissions it demands before installing!

I'm sorry but I can't give more than 1 star. The robotic voice is awful.

manual input of relevant text will not read automatically

Additional TTS voices are not available, only voices in the machine. A TTS software like Balabolka with some voice engines (ex. IVONA) installed is the way to go for people who are serious about TTSs, not this.