I am not entirely clear, but the .7z file is obviously a compressed archive of the installation files. It could be that the .exe file will expand the .7z file in the installation process. Al I can say is to make sure the files are in a folder with nothing else in it before running the .exe file.
If it sounds like I have missunderstood your problem, then please try again.
The serial number is are not in a file. The installer expects you to enter it.
I have not heard of anyone doing an upgrade between Photoshop Elements and Photoshop CS5.1 before, but if it's a legitimate Adobe offer, the installer should allow you to enter the serial number of the qualifying older product during the installation. Watch the dialogs carefully for the prompt to do this. For upgrade installations you really never have to have the old software installed first - it's all done with the serial numbers.
I am trying to activate PS 5.1 on a new computer. Following your advice to someone else, I entered the PS5 serial number and the CS3 thsat it was upgraded from. However, I get th mssge that installer can not find CS 3. Do I need to download CS3 to the new computer as well? That, too, is an upgrade from an earlier version that is long gone and I do not have a serial number for it.
No need to install CS3. THe serial number should be just fine. Need to enter the qualifiying product. Is 5.1 and upgrade or a different product? Perhaps you need s/n of CS3.
The serial number did not work. It was looking for the appication CS3. I instaled CS3 photoshop and now it wants the quaifing ap for that, which I no longer have.