I have tried everything mentioned on various websites, but I keep getting a purchase failed, or the window counter just spins and just back to the first screen.
Hello @Swansong,
Welcome to the Lost Ark forums, its a pleasure to have you here! 
I’m sorry to hear you are not able to purchase crystals.
Could you please tell me which troubleshoot have you try so far? Also let you know this is a known issue with the commerce server. Here the last update:
I’ll be waiting for your reply! 
Resetting overlay
Run steam in admin
Clicking on purchase button repeatedly
Removing discord overlay
Forced steam stop
Nothing has worked
Thanks for replying!
Please try the following steps:
- Close Lost Ark completely
- Force Stops Steam
- Run Steam as administrator
- Verify game files on steam (Steam Support :: Verify Integrity of Game Files)
- Re-lunch Lost Ark
If the issue persist, keep an eye on Official News - Lost Ark Forums for updates on this known issue.
I really appreciate your patience and understating! 