Hello @Hazirah-Syazwani0
The only way to pay on Airbnb is with a credit card I believe. This "problem" of not being able to pay online is sometimes a way for guests to get the host to accept a payment off line. Write back to your guest on the Airbnb message system that they should contact Airbnb customer service and they will look into it. Give them the phone number for your country if you have it.
Tell them that it is Airbnb that handles all the transactions on line and not you.
If you are new to Airbnb, be cautious as new hosts are sometimes targeted by bad guests. Hopefully this is not the case of course but you did well to check first.
Let us know how this turned out for you
All the best
Joëlle