Hello from Poweramp support team!
Starting from Poweramp build-550 there is no Unlocker for website purchase, and Poweramp is unlocked in-app via Settings => Already Purchased? => Website.
Detailed instructions:
0. uninstall any other versions of Poweramp Full Version Unlocker if you have them
1. ensure your Internet connection is working on the device and you can open http://powerampapp.com
2. ensure your Google or Email account (as specified in purchase confirmation email from PayPro Global) is registered under Android settings => Accounts
3. ensure you have Poweramp build-550 or later from Poweramp website (http://powerampapp.com/download-poweramp). Play builds don't have non-Play purchase support
4. in Poweramp Settings use Already Purchased? => Website and type in Google/Email account and Order ID (as specified in purchase confirmation email from PayPro Global).
More details - Restore Poweramp Purchase
Thanks!