To transfer the license, you will need to install the eLCC on the Mac. You will need the new Soft-eLicenser number to request a reactivation through your MySteinberg account.
You can transfer the license to a USB-eLicenser. This will enable use on multiple computers. Just keep in mind that it’s not a reversible process.
As far as the Elements 7 Mac installer goes, you will probably need to contact support (through your MySteinberg account). Or, if you get lucky, a mod might stumble across this thread and help you out.