To access and redownload already-purchased Magix products go to your Magix account, log in and go to My products. Find the listing for the specific software and you should find the installer and serial key.
BUT, Photos on Cd & DVD 3 is now very old and so may no longer be available, or compatible with any recent version of Windows; Photo Manager 17 is still the current version so should be shown in your account.
You write that you want to upgrade photo manager to photo deluxe; was this a mistyping? PM and PS are two entirely different programs; however, PS is an upgrade to Photos on CD & DVD so you should be eligible for the upgrade price. You may need to quote your serial key for the older program in order to benefit from the reduced upgrade price.