: Adobe's activation servers for CS3 were officially shut down in 2017 . Even with a legitimate old serial number, installing it on modern systems is extremely difficult and often technically impossible without specific workarounds provided by Adobe years ago (which are no longer active).
For those attempting to run CS3 on legacy hardware, the original minimum requirements included: : Intel Pentium 4 Go to product viewer dialog for this item. PowerPC G4/G5 RAM : 512 MB (1 GB recommended). Storage : 2.0 GB - 2.5 GB of free space. : Adobe's activation servers for CS3 were officially
If you are looking for a "good guide" to learn the software, you should rely on official documentation and verified archives rather than risky downloads: : Adobe's activation servers for CS3 were officially