I bought the game, but I delete it. How do I get it back?
If you bought the game on itch.io there's a "download" button at the top of the page when you're signed into your account. You should be able to download it from there, or get a Steam key for it from the same place.
Of course, if you can't use Steam (there's a few reasons including medical risks in the past 2 years), or have good reason not to (which there's been even more reasons for over an even longer time), then the itch.io version technically works, but doesn't provide full functionality. The devs stopped supporting it quite a while ago, and in spite of promises to the contrary, have done nothing to fix it since.
You can't use an account with the itch.io version, and that locks you out of free chat, personalised name changes, and many other basic elements of the game. If you want those features on PC, you either need to use Steam or refund your itch.io purchase and buy the game on Epic instead.