Extract the project backup (.apb, .csp, .pcd, .bin) and use a hex editor or dedicated tool:

To conclude the search for the – it does not exist as a single file or simple code.

: Often uses the username admin with no password by default.

Searching for default passwords for PLCs (Programmable Logic Controllers) and HMIs (Human Machine Interfaces) often reveals that many manufacturers use simple, factory-set credentials. If you are locked out, these "keys" are often the first step to regaining access. Common Default Passwords

Unified HMI default Username and Password??? - SiePortal - Siemens