If you are running a recent version of Photoshop (CC 2017 or later) or a recent OS, you should use the latest Camera Raw compatible with your software instead of 9.1.1.
You cannot use ACR 9.1.1 with just any version of Photoshop or Lightroom. It is tightly version-locked. Camera Raw 9.1.1 Download
Adobe does not keep old installers on its main public download page, but they are archived on Adobe’s official servers. Here is the only safe method to download Camera Raw 9.1.1. If you are running a recent version of