The Rabbit app likely offers a download feature for offline viewing to its premium subscribers. This is the only legal way to download episodes for offline viewing.
When users search for a "free download" of a web series, they are almost always looking for pirated versions. This is a dangerous path. Piracy is the unauthorized use, reproduction, or distribution of copyrighted material, and it harms the creators who work hard to produce the content you enjoy.
The "Mohini" web series has garnered a mixed but generally positive response from viewers, typical of content in its genre.