Basilisk Portable for Flash . Flash NPAPI never received a 64-bit version. Ensure you are running the 32-bit portable build even on 64-bit Windows – it works perfectly.
To ensure Basilisk or the plugin doesn't automatically update and break your legacy compatibility: basilisk portable with flash player
You cannot download Flash from Adobe anymore. Adobe's official uninstaller actively scrubs it. However, the Internet Archive (archive.org) and community preservation projects have archived the final, safe versions. Basilisk Portable for Flash