There are multiple ways to access ‘Data Downloader’. One of them is directly from Trendlyne’s home page. 

Hover over the ‘Markets’ tab on the home page and click on ‘Data Downloader’ under the ‘Tools’ section, as shown below.

Alternatively, ‘Data Downloader’ can be accessed through ScreenersPortfolio, and Watchlist tabs.

Any selected screener/portfolio/watchlist will have an ‘Export’ option. Click on it to see ‘Data Downloader’ in the drop-down menu.