Are you refering to the Creative Cloud monthly subscription?
No, no ; I have a complete license for LightRoom 5, received with my camera.
I am going to guess that the link should end in .exe (one-dot-exe) rather than ..7z (two-dots-seven-z)—the two-dots are wrong for sure and there is an EXE not a 7z at that URL:
Once downloaded you can use the 7-ZIP application to extract the files from the EXE.
It is possible that the tech meant the following .7z URL which is for LR 5.5 and the Creative Cloud version not the serial-number-licensed version, but since you’re dealing with a serial-number-licensed version, hopefully not, it is the one URL that has a .7z on it:
I think i will never know what was different from the first try I installed LR5...
But, Thanks to You, that's working !!!
I'm very happy and would let you know you have all my consideration ^^
If what is working is that LR 5.0 is able to be licensed with a European serial number, then what you probably want to do, now, is update LR to 5.6 from http://www.adobe.com/downloads/updates/ or using Help / Updates in LR, itself.