Don't fret buddy, I wrote you this easy to follow guide in the Gearbest thread. Don't know if you saw it or not.
https://www.head-fi.org/threads/hal...1-xiaomi-mini-25.832367/page-36#post-13840810
I know you feel like you gotta jump through a lot of hoops, but really there's only 4 things you need for Gearbest:
1. The code is on the specific item posted. For example, if there's a code for grey ZS5 with no mic, you can't pick blue with mic.
2. Some of the codes are for locked to specific countries (for shipping cost purposes). Some codes will say "these countries only", and others will say "no country restrictions" or will not say ANYTHING about countries (which, in that case is also no country restrictions).
3. There is specific times on the codes. For example, if it says it starts at xxyy time and date Beijing time, you have to abide by those parameters. I explain in more detail in the link I posted above.
4. There is inventory limits on the item. It is says "50 pcs only", then once 50 are sold the code is gone. I've herd that Aliexpress and other DEALERS often buy in bulk FROM Gearbest, because the GB price is often lower than THEY can buy the stuff from their wholesale suppliers from. Also you figure there are 7 billion people in the world, so 50 pcs only won't last too long.
Contrast this to Aliexpress 11.11, where you DO have to jump through hoops, playing games to win coins, trading coins for coupons, stacking this or that coupon, screaming into microphones, mobile games are different than PC games, etc. What a PITA.
Anyways, if you are still having trouble, lemme know and I'll do my best to help.