Is it mandatory for me to link my bank account to PayPal if I want to make a donation? What if I don't want to? ...then I can't donate?
You don't have to. That is if you want a PayPal account with certain functions. Once you get redirected to PayPal's site, you can click "Don't have a PayPal account?" Then put credit card or debit card info. (There is also BillMeLater, which may not work outside the US.)
Sorry I still don't understand what I have to do. I made countless online purchases and payments before but never met with a procedure like this... Thanks.
I saw you got to the PayPal screen. They give you two options. 1) To log into your PayPal account. 2) To fill out the form and pay without an account. The second option is what you want. You give your basic info and click submit, and then you give your credit or debit card info. Then you should be done with the donation. They will invite you to create a PayPal account, but there is no need. I put a green box around the second option. The second option should be default, because PayPal could tell that you haven't logged into an account recently. PayPal processes your credit (or debit) card securely. They are basically like a huge online bank, and it should be safer than giving your card to pay in a very large store.