Edit: Please follow this guide instead. I deleted my write-up since some details were misleading and this guide is much better.

Thank you to u/fwosh for sharing your guide!

Edit 2: Here are a couple pitfalls to watch out for so you don't have to trawl the comments below. 😅

1. Make sure you pay for your tickets online and don't select "Pay at counter". If you do, you'll be required to go and pay within two days in person, which probably isn't possible for you if you're on this page :') You can do this with a debit/credit card from any country.

2. If you get to the captcha step during checkout and it tells you that you're not allowed to buy more tickets, it's possibly because you had two tabs of the checkout page open.

3. You can only buy tickets in one transaction per month. Even though the maximum allowed tickets in a single transaction is 6, you can't buy 4 at once and then come back to buy 2 more.

Thanks to fwosh, Ok-Rest5952, Crazy_Broccoli_1961 for sharing these issues!