If you download the original version 1.0.0 IPA file, it will not work on a modern device. To play the game today, your IPA file needs specific updates and modifications:

: Pre-baked files that bypass the "Update Failed" screen caused by dead Rovio servers. Content Restoration : Re-enabled events, tournaments, and daily challenges. Where to Find Files

If you have a jailbroken iPhone on iOS 14 or earlier (or a checkm8-compatible device on newer OSes), you have the easiest path.

The best place to find working, community-patched IPAs is through specialized Reddit threads. Active users often share links to 64-bit compatible IPAs that work on modern iOS 12–18 devices.