Which plugin? If you would give us the GitHub URL, we can check to see if there is something unusual that might be causing you trouble.

Also, just for reference in case something else is odd, please open Notepad++, click the question mark at the right end of the menu bar, select Debug Info… and click Copy debug info to clipboard, then paste what you copied into a reply here.

@PeterJones I downloaded the plugin from github and put it in the plug in folder for notepad++, but had no luck. Notepad++ didn’t recognize I installed the plugin.

Did you put the DLL directly in the plugins directory, or did you put it in the correct subdirectory under the plugins directory, like my last message and the user manual both explain?

update: … And after you put it there, you must restart Notepad±, because it only checks for plugins when the app starts.

The whole “Notepad++ will restart to finish operations” window popped up, and then restarted, but plugin was not installed.

My first debug step would be to see if your user has write permission to the <install_directory>\plugins\ folder. If not, you need to run Notepad++ as Admin to be able to install the plugins using Plugins Admin tool. (Then go back to a normal run to just use it)

What am I doing wrong?
How can I install plugins?

Most likely fix your permissions.

I even tried manually installing the plugin, but nothing worked.

You don’t tell us what you did to manually install them, or how it didn’t work: whether the failure was because the files wouldn’t write (which is obviously a permissions issue), or you didn’t put the DLL for a given plugin in the right directory (if your plugin uses Blah.dll, it needs to go as <install_directory>\Plugins\blah\Blah.dll – the directory name must match the name of the DLL (without the extension).

Read the User Manual’s How to Install A Plugin for more.