Thanks for the reply. I did everything in that guide and even started a live chat with a Ledger employee this morning. It seems I have set up everything correctly as per the guide you mentioned and I should indeed contact Kucoin as per why they don't support withdrawals of HBAR. I find it a bit rude/weird of Kucoin to state ''invalid address'', confusing me for quite some time, whilst they probably just don't support withdrawing the token to external wallets.