Android 5.1 did not have native app locking. WhatsApp Plus adds a built-in lock for specific chats (e.g., hide a private conversation behind a pattern).
The most significant cost of using WhatsApp Plus is the loss of guaranteed security. While official WhatsApp uses end-to-end encryption to ensure only the sender and recipient can read messages, third-party mods often route data through their own servers. Data Vulnerability: download whatsapp plus for android version 5.1
Do not use WhatsApp Plus with a business-critical phone number. Always back up your chat history to Google Drive via the official app before switching. Android 5