If you are getting an ad blocker pop up, please try one of the following:
Log out in your Playfull account and disable adblockers (if you have one). Relog in to your account.
Try using another browser.
If you are using Google Chrome or other Chromium-based browsers, go to Site Settings and allow 'Intrusive ads' or other similar ad-related settings.
If you are using Firefox, click the shield icon to the left of the URL line to disable 'Enhanced Tracking Protection' for Playfull.
If you are using Opera One, disable Privacy Protection in the top right icons.
Try to reserve/mint using the Metamask app built-in browser.