Unable to outline the cell with the cell outliner plugin downloaded from imageJ website

You are trying to execute a Java plugin as a macro.

Please read the description how to install the plugin:

https://imagej.net/plugins/cell-outliner.html

Hi

I have already installed the plugins based on the descriptions and the result is still the same.

Just save the file to the ImageJ plugins directory (with *.java extension). Then open the file, compile and run it:

Plugins->Compile And Run…

Open a stack before (seems to be required) else you will run into an error with this plugin (line 138).