It's not the button you need to set up, Itch.io projects can receive donations by default. As Leaf pointed out above, you need to configure payments on your account. You can do that in the Payment Processors section of your account settings.
In unrelated news, next time you have a problem, please start a new topic rather than necro-ing a 9-months-old thread. I only noticed your post by pure chance. As you can see, the creator you replied to wasn't so lucky. :)
ugh... well... I adjusted up payments on my account, but under my project there is no "donate for this project" button, which Abduki has (https://abduki.itch.io/gravity-box). So... I need to add it in some other way?
p.s I swear, it was the last question, starting from the next I will open a new thread!!
p.s.s. can I collect donations, if I didn't upload the game yet? I mean something like an advertising page, where is no game itself, but you still can donate to author
No, by default the donation button is enabled. Make sure you haven't ticked the "no payments" checkbox under Pricing on your project's edit page.
And no, you can't collect donations for a web game that isn't there yet. For a downloadable game, I think you can mark some of the files as placeholders for preorders. Can't seem to find the checkbox right now however.
