Thanks for reaching out to the Community for support. I'm happy to lend a hand with installing QuickBooks Online to your desktop.
You can directly download the app using this link: http://quickbooks.intuit.com/apps/. Scroll down to Get the QuickBooks Windows App section and select Free Download, and then select Download Now.
To start installing QuickBooks App for Windows, follow the steps below: 1. Double-click the file you downloaded to launch the installer. 2. Hit Next, then choose Agree & Install. 3. Wait for the installer to run the rest of the way through. 4. Click Finish.