I'm curious about how to pay fees online in Korea!

Hello! I'm a foreigner who has been living in Korea for 6 months now, in Itaewon. I heard that from March 3rd to 6th, I have to pay an application fee, but during that time, Korean banks will be closed due to a nationwide holiday. Is there a way to make the payment online? I'm not sure if I need a card or some other method. I'm a little worried. From what I've found, it seems that online payment with a card issued overseas is possible, but I'm wondering if there are other options. If anyone has had a similar experience, please help me out! If you know which card is best, or if there are other payment methods available, please let me know. Thank you!