These tools require a modern iOS device to install the server component.
This is the biggest hurdle. Even if you install the app, WhatsApp’s servers often block "expired" versions from verifying your phone number. whatsapp ipa for ios 9.3.5 download
Have you successfully installed WhatsApp on iOS 9.3.5? Share your experience in the comments below (or on Reddit at r/legacyjailbreak). These tools require a modern iOS device to
Sideloadly is currently one of the most reliable tools for installing IPAs. Connect your device to your computer. Open Sideloadly and drag the WhatsApp IPA into the tool. Enter your Apple ID (this is required to sign the app). Have you successfully installed WhatsApp on iOS 9
If you are researching this for a project or looking to revive an old device, here is the current state of the "paperwork" on this topic: Server-Side Killswitches