This article will show you how to install plugins for Adobe After Effects. If the plug-in doesn't come with installation instructions, just copy the file to the Adobe After Effects plug-in folder. Later in the article, you will learn how to download the plugin and copy it to the appropriate folder for After Effects.
Steps

Step 1. Download the plugin
Some plugins are free to download, others are not. After Effects plugins are available for download from a number of sites, including videocopilot.net, videosmile.com, and third-party plug-ins for Adobe After Effects. Select a plugin and then click on the download link to download it.
After Effects plugins are usually downloaded in ZIP archives

Step 2. Open the ZIP archive
Double click on the ZIP archive with the left mouse button to extract and open its contents. The extracted files will be automatically placed in the Downloads folder.

Step 3. Open the folder corresponding to the operating system of your computer
The ZIP archive contains several folders with files for a particular operating system. For example, you can find the following folders in the archive: Plugin for Windows 32-bit, Plugin for Windows 64-bit, Plugin for Mac 32-bit, or Plugin for Mac 64-bit.

Step 4. Copy the plugin file to your desktop
Drag the file to your desktop, or right-click on the plugin and select Copy, then right-click on the desktop and select Paste.

Step 5. Open a new Explorer window

on Windows or a new Finder window
on macOS. On Windows, click on the folder icon on the taskbar. On macOS, click on the blue and white emoji on the left side of the Dock at the bottom of the screen. This will open a new window for viewing files on your computer. On Windows, the Adobe After Effects folder is typically located at C: \ Program Files \ Adobe \ Adobe After Effects \ Support Files \ Plug-ins. On macOS, the plug-ins folder is located in Utilities / Adobe After Effects / Plug-ins. Right-click the After Effects plug-in folder, select New and then Folder. Name the folder with the name of the plugin. For example, if you want to install the "VC Reflect" plugin, name the folder "VC Reflect". Drag the plugin file from the desktop into a new folder, or if you copied the file, right-click inside the folder and select "Paste" to copy the plugin to a new folder. The plugin can be enabled from the Effects menu in the panel at the top of the window.
Step 6. Open the After Effects plug-in folder
Step 7. Create a new folder for the plugin
If you have a Mac that doesn't have a right-click mouse, or only has a touchpad, press inside a folder with two fingers to play the right-click
Step 8. Copy the plugin to a new folder