Is this possible? I have Listrak_Remarketing already installed in an instance, but it does not show up under "Magento Existing Extensions" under System -> Magento Connect Manager. So, I'm assuming this was manually installed.
I tried upgrading this extension via Magento Connect, but it does not allow it because it's checking for existing files, and there are existing files.
Update 1: For reference, this is the error
Checking dependencies of packages CONNECT ERROR: Package 'Listrak_Remarketing' is invalid './app/code/community/Listrak/Remarketing/Block/Adminhtml/Abandonedcartreport/Grid.php' already exists
Update 2: I found a site that lets you download the extension given the link obtained from Magento. Answer is below.
Update 3: Also, it looks like you may have a compressed extension file downloaded after all here even if it fails to install via Connect -->