UnityPlayer.dll Missing?

[wlsuszmrist]

Hello, I recently downloaded and ran an app as an administrator, but got an error message saying that I basically needed UnityPlayer.dll. Not knowing what it really was, I searched UnityPlayer.dll download online and got to this page:
https://www.dll-files.com/unityplayer.dll.html.

I downloaded the first link, and after making sure the files were extracted, I tried running the original app again. However, I got the same error message, again. I don't know much about computers, so I don't really know what's going on.
Could you help me? Thank you!