App can be accessed on office 365 but the desktop app is not installed on laptop. When trying to install it take me to Microsoft Store which it has been blocked by company. Some laptops have it where others don't.
AFAIK, the To-Do Desktop app is only available from the Microsoft Store. It is blocked in my organisation too.
Recommended to contact your admin and get them to get the app on your machine. If it is blocked, you won't be able to access the download. Even if you did manage to find a file elsewhere its always recommended to download and use the authoritative copy from the windows store.