Exactly which version of Samplitude Pro X do you have? The DVD label would suggest this might be version 1? The current latest is 8 so yours is likely to be a very old version, I think.
Assuming you previously had it installed, registered and activated, you should be able to access the download, assuming it is still available - it may well not be due to its age - by going to your Magix account, logging in and going to My products. Find the listing there for Samplitude Pro X and see whether there is an available installer download. Also note any serial key listed there.
If you have not previously installed, registered and activated the software you will need to email infoservice@magix.net, explain what you wish to do, giving as much detail as you can about your original purchase of the program, and ask if they can assist you to retrieve your software.