Have you installed the program on other computers that you have used in the past? Have you previously registered the program.
Or have you only just purchased it? If so, what was the source of your purchase?
If you are having trouble with a legitimate registered copy of the program, your best bet is to go to Adobe.com and click the blue Contact Us button which appears under the Support menu. You can then chat with Adobe support and they will be able to deactivate any copies of the program that are active on other computers to which you no longer have access.
I purchased PS Elements on a disc a few years ago. I only installed it on my pc. I am retired and do not have any other PC. I had slowness issues with the PC and had it cleared down. I then reloaded all my software discs. Because I could not open elements I Uninstalled it again and loaded it And it will not open, see photo below.