If you are trying to run old VB6 code, consider twinBASIC or VB6-to-.NET converters instead of clinging to the IDE itself.
Before resigning yourself to hunting for a “Visual Studio 6.0 ISO with key,” consider whether a modern tool can replace your legacy workflow: Microsoft Visual Studio 6.0 ISO With Key
After installation, you will likely get "Component not found" errors when compiling. You need to run the VS6 SP6 (Service Pack 6) to modernize the runtime libraries for NT-based systems. Download SP6 from the official Microsoft Update Catalog (still available). If you are trying to run old VB6