While Apple technically has a feature that offers "Last Compatible Version" downloads from your purchase history, many developers have pulled their legacy binaries from Apple's servers entirely. Where to Find Working iOS 7.1.2 IPA Files
Use Safari on your iOS 7 device to navigate to an archive site (like Archive.org) and download a compatible IPA. Choose once the download completes. ipa files for ios 712
(now largely deprecated) and its successors like Sideloadly remain viable options. Cydia Impactor requires a computer but no jailbreak: download Cydia Impactor, connect your device, drag the IPA file into the Impactor window, enter your Apple ID credentials, and wait for the installation to complete. Keep in mind that free Apple IDs provide only 7-day certificates and a limit of 3 sideloaded apps at a time. While Apple technically has a feature that offers