Enter the email address you bought with. Every key belonging to that address goes out to it.
If a purchase belongs to this address, the mail is on its way. Check the spam folder too.
One mail per address every ten minutes, no more.
That does not look like an email address.
Mail is not set up yet, so nothing can go out right now. Write to support from the email address you bought with.
The licence service is not answering. Try again in a minute, or write to support.
You paid through Stripe, and the Stripe receipt carries the address the key went to — use that one here. If that does not help, write to support and name the date of the purchase.