You need WhatsApp or earlier (the last versions supporting KitKat). Recommended sources:
Do use random APK sites. Only trusted archives: Whatsapp For Kitkat 4.4 2 Download Old Version
If the old version of WhatsApp refuses to connect, consider these alternatives: You need WhatsApp or earlier (the last versions
Since you aren't using the Play Store, your phone will try to block the installation by default. Even if you bypass the initial "version too
Even if you bypass the initial "version too old" warning by changing your system date, the app will typically fail to register new accounts or link existing ones. Security Risk Using outdated versions from third-party sites like leaves your device vulnerable to unpatched exploits. Review Breakdown 1. Installation Experience (1/5)
: Go to Settings > Security and toggle on Unknown Sources . This allows you to install apps from outside the Play Store.