I got 100 downloads of all my projects. But I did not receive any donation :(

Sorry to hear that. It takes some luck, too. Be patient and keep promoting your games. People can't even donate to your new visual novel, because you've disabled payments. :)

I think that people won't leave a donation until they know they'll enjoy your game, but after they have downloaded & played your game, they will probably forget t ogo back and give a donation. So maybe at the end of your game you can give them a reminder? 

At the end of my game I give a reminder for people to go to itch.io & give a rating. Surprisingly quite a few people do! I think they just need to be reminded!

Agree with the comments above - give people time to play your game and see if they like it or not

My most popular game here has about 5000 downloads and 30 payments. I'm sure there are a lot of factors that affect the ratio, but generally I wouldn't expect most downloads to result in payments (otherwise it woud make more sense to just charge a fixed price for it), I'd focus on spreading the word and getting more downloads.

I'm frankly embarrassed to say, but we have certainly reached the conclusion that hoping people will donate for a free game is not the optimal strategy to make money! Especially when the donation screen appears before they've even played the thing...

And our games are rated pretty well- 4.3 and 4.5 for our last two...