You do not download Trello
Trello is run as a service, it's not server based software you can run yourself, so there is no download of Trello.
People have written clients for it, for various platforms, and you can download and run those on your own servers, but they are not Trello.
What are you trying to achieve here, with your "download"? We may be able to point you at something that solves your problem if we know what you're really trying to do.
You can use Trello with your browser (Chrome, Firefox, Safari and Edge), Android app, iOS app, Desktop version (Windows and macOS), check more information here https://help.trello.com/article/735-what-browsers-and-mobile-platforms-does-trello-support
Regarding the Trello Desktop version (Windows and macOS) you can only download them in Microsoft Store or Apple Store, check here https://help.trello.com/article/1095-trello-desktop-apps
To download Trello for Windows 10, go to https://www.microsoft.com/en-US/store/p/trello/9nblggh4xxvw?rtc=1
To download Trello for macOS, go to https://itunes.apple.com/us/app/trello/id1278508951?mt=12
Check how to use Trello for Android on https://help.trello.com/article/730-trello-for-android
Check how to use Trello for iPhone on https://help.trello.com/article/711-trello-for-iphone
Check how to use Trello for iPad on https://help.trello.com/article/720-trello-for-ipad
Note: you need to have a Microsoft account to be able to log in and download the Trello Windows version. You need to have an Apple ID to be able to log in and Download the Trello for macOS.
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