What game are you having trouble with? You might want to ask the creator of that game, specifically. Also, are you using the itch.io app or a web browser? If the latter, which browser and version? On what operating system?
The Unity webplayer plugin has been deprecated by Unity, which makes it difficult to run some of the older games on our site. Are you sure you have the webplayer plugin installed?
yes it is installed
and when i try to download it by using inspect element and searching .unity3d when i try to download the .unity3d file it allways fails to download