Many websites claim to offer a 50MB version of the game. Upon download, the user receives a corrupt archive or a dummy file designed to trick the website's automated ranking algorithms. These files cannot be opened or installed.
You might see "highly compressed" versions of Warband online, but these often come with risks like malware or broken files. Since the official game is only about 1GB, "compressing" it further yields diminishing returns. Instead, you can download the official trial version from TaleWorlds mount and blade warband highly compressed top
Ensure your PC meets the basic specs (it runs on almost anything). Many websites claim to offer a 50MB version of the game