Origin has a bug where it tells people that have a mixture of DVD and Download Version to uninstall the base game and get the download Version instead.
This is NOT necessary
Here's what to do
To be able to install the download version without reinstalling despite that message, do not click on the Download button in Origin, click on the “i” (information) button. This will open another window that also has a download button. Click on that to install.
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