It doesn't work what can i do ?

The setting that control the sound is "Game effects", when the "global" box is not ticked, if it is ticked, then the settings that control the sound is "Alerts". That may explain why some sounds aren't heard.

If it's something else , I'm sorry, i may have made a mistake this is my first mod, let me know in the discussion part, i'll try my best to assist, i'm still very enthusiast.

It does work but sound like the robot has a slight disfunction what can i do ?

turn off the polyphony :)

How can I use this ?

One way is to have speakers set up to say one specific sample, "Welcome", then another speaker "2", then another speaker "outpost", then another speaker "20" then another speaker "4". "Welcome to outpost 24".

Another way is to have the same speaker say all the sample from the same category, this is more useful for the numbers. A pulse signal will trigger 1 sample, the value of the signal or the "pitch of the note" allow to say a different number or word. Those are sorted by alphabetical order when possible.

The robot look like it's singing, but there is no singing sound, i'm disappointed what can I do ?

There's some extra sample that are a bit sung no ?
For some more singing, you'd need the DJRobot mod :
https://mods.factorio.com/mod/DJRobotMIXTAPE1/

There is only male and female voice, what about a neutral voice ?

You can try to play both voice at the same time.

There is only english, what about other langages ?

I don't know, for some i wouldn't be able to tell when to split the words or even which string to use as it was done with AI reading a full text. I would welcome the occasion to learn because i can only do so little. I can provide the list of words used or any file or script just ask in the discussion part or send pm to mmmPI on the forum.

Isn't the list of word too short ?

That's not really a question, but yes, it is too short, some will probably be added over time, when i realize i need them, or if some are suggested.

I want to contribute how can i do ?

Suggest some words, provide funny example of use case.

It doesn't sound like a robotic voice, is this really a robot ?

I was not able to verify more than what the website allows, i think it is a real robot that was used, but maybe it is a group of skilled humans.