For v281 to install, your device must run . Newer iOS versions will fetch a later build (e.g., v321 for iOS 9).
Installing djay 2 for iPhone v2.8.1 via an IPA file is primarily a solution for users with older hardware or those who prefer the legacy "djay 2" interface over the modern subscription-based djay Pro for iOS Core Compatibility & Features System Requirements djay 2 for iphone ipa v281 work