Open your browser’s folder or use a File Manager app to find the downloaded .apk file. Tap the file and select Install .

"Step 3 – After install, go to Play Store > Settings > turn off auto-update. Otherwise, it updates overnight."

: WhatsApp currently requires Android 5.0 or newer . Version 2.23.6.x was generally designed for these systems, but devices running extremely old software like Android 2.3.6 (Gingerbread) have been officially unsupported for years.

Try to update to the latest version as soon as feasible to ensure you have the latest security patches.