I have not found very clear instructions or support on how to download and install the QuickBooks extension for CiviCRM in my WordPress + CiviCRM installation so I am going to share the steps I took to accomplish this here, for future reference for myself as much as anyone
First, this is the extension that I used – https://github.com/NileemaJadhav/Intuit
Click the “Download” button on the right hand side of the page to download a zip file.
Once the zip file has been downloaded, expand the folder.
Inside the expanded folder, named Intuit-master, you will see another folder called org.civicrm.payment.intuitquickbooks. Upload this folder and its contents to your designated CiviCRM extensions directory.
Using your FTP client of choice, open the org.civicrm.payment.intuitquickbooks folder which you just uploaded, and move the file named IntuitQuickbooksIPN.php to this folder: <your website root>/wp-content/plugins/civicrm/civicrm/bin
Now log into your WordPress dashboard and click CiviCRM in the sidebar.
In the CiviCRM admin panel of your WordPress dashboard, navigate to Administer > System Settings > Manage Extensions. Once on this page, you will most likely have to click the “Refresh” button to see the Intuit extensions listed as available for installation, at least I did. After you’ve refreshed the list of extensions available for download, click the “Install” link next to the Intuit extensions to install it.
Once the extension has been installed, navigate to Administer > System Settings > Payment Processors. Click the button to add a new Payment Processor, and now in the dropdown list next to “Payment Processor Type“, you will see Intuit Quickbooks as an option.
Here is a tutorial with further information on getting your QuickBooks extensions configured – http://wiki.civicrm.org/confluence/display/CRM/Setting+up+Intuit+QuickBooks+Payment+Processor+for+CiviCRM
Hope this step-by-step tutorial saves someone the time I have spent trying to get this working