If you select “Collected by Itch”, then you would need to complete an interview, to decide how much of your money will be paid to taxes. That way, Itch.io takes care of paying sale taxes to the US based on your sales.
If you select “Direct to you” instead, money from sales will go straight to your account, but you are responsible for paying sale tax in the US.
Either way, you are still responsible for paying income tax in your own country, which is a different process depending where you leave. If unsure, you can always ask a professional.
You can read more details on Accepting Payments and Getting Paid.