If you're looking for a free and legitimate way to access this book, I suggest checking the following options:
With the advent of the internet, the medium shifted entirely.
Distributing and downloading pirated scans of books violates intellectual property laws. Users should always look for legitimate, authorized platforms when consuming regional literature. Conclusion: Browsing Safely Online
Project Gutenberg : A vast library of free, public-domain books, including classic Bengali literature.
: If you have already downloaded the file, delete it immediately without opening it.
Downloading and opening such a file can lead to several severe security compromises: