Help With CS5 Master Collection

I have an older version on CS5 Master Collection that I believe was installed in 2009 or 2010. I do not want to upgrade to any new versions. I had to reinstall it on a PC that we upgraded. However when I try to open the program it keeps trying to get me to activate my online subscription services, etc. I do not want or need any of the online services. I have an older serial number that I used to reinstall the program, but I cannot open any of the programs. It keeps offering me to do a trial version but again this is the same file that I used originally it has just been stored in my original PC as a file. I have no idea where the original CD is any longer, or the original package as it was 9 or 10 years ago. I called Adobe and they no longer support the CS5 and recommended that I go to the forums to see help.