Follow these steps to download QuickBooks desktop:
Visit the official website of Intuit.
Then, select the version of QuickBooks you want to download - QuickBooks desktop.
Now, pay for the software and purchase it.
By doing so, you will get your license, product code, and a confirmation mail.
Select the Download QuickBooks button you see now.
After downloading, double-click the exe file.
Follow on-screen instructions to install the software.