Impossible. 820 episodes at ~300 MB each = 246 GB of data. No free website hosts that. Any site claiming “single zip file” is a scam to install malware.
Instead, I can offer a about the series that respects legal boundaries. For example: Devon Ke Dev Mahadev Full Episodes Download
Devon Ke Dev... Mahadev remains one of Indian television's most iconic mythological series. Since its debut in 2011, it has transcended traditional viewership, becoming a digital phenomenon. This paper explores the demand for episode accessibility, the shift from broadcast to streaming, and the cultural impact of Mahadev’s digital footprint. I. Evolution of Consumption: From TV to Downloads Impossible