@Mahi86
I don't know if Seoul has a tourist licencing programme, but we do here in Mallorca. It's obligatory to have one or else you can be clobbered with huge fines and shut down.
Airbnb occasionally demands that we provide proof of licencing with threat of delisting. No problem, we have one and send them the proof.
However, ironically, Airbnb is chronically under scrutiny for listing illegal unlicenced holiday lets, and has been frequently fined for not removing be them from the platform.
So, it seems that Airbnb's demand for proof of licence may just be an unenforced show of goodwill to local authorities (?) The documents they collect are apparently unverified and may not even be stored anywhere. It's just a checkbox exercise.
If you have licence, send it to them (it usually takes 2-4 uploads over a period of several weeks, after being requested again and again before they recognise you've done it already).
If you don't need a licence in Seoul, then send them a tax statement or something else with a government logo on it, preferably written in Korean. They won't likely know the difference, and will check you off as "completed".