How to Install voices for other languages for Read Out Loud?

Hi!

My mother needs to use the Read Out Loud function but I'm not able to help her.
My adobe reader has the option for changing the voice (pt-br/eng) but I don't know if that has to do with my version of Windows that it's also in portuguese.
Her Windows is set to english but Adobe Reader on her computer is downloaded by the pt br version but will show only the voice for english (Zira) available.
Can somebody help me how to install the portuguese BR voice plug in from a trustful source? All the ones I found I got comments on them saying they contained viruses.

Thanks!