If you specifically need version 4.12 (often for compatibility with older Windows 7 or 8.1 environments), you can find it in the Citrix archive: : Receiver 4.12 for Windows . Specialty Versions :
: Always restart your PC after the installation completes. 💡 Receiver 4.12 vs. Workspace App citrix 4.12 download
You are using that does not support the library requirements of the latest Workspace app. If you specifically need version 4