About 10 minutes after the enrollment, I got an email, telling me that my purchase was being processed.
1 hour after I got this email, I got another email about the taxes, and there was a PDF attached to it.
I checked my account on Apple's website, but apparently, my account wasn't activated.
They say it should take 48 hours, but there is still nothing. In addition to this post, I contacted Developer support, they should answer me soon.
How long does it take for an account to be validated? Does it take longer if you're not in the U.S.?