1. Open webpage: videohive.net/downloads

2. Find the project and click to Download >> License certificate & purchase code (text).

3. Open license file and copy Item Purchase Code and paste into dialog field.

4. Click on activate and enjoy.

More details here

1. Download and install ZXP here

2. Run ZXP

3. Drag and drop file *.ZXP in the package into the ZXP tool and let it install automatically.

YouTube Tutorial here

1. Run the extension by the Windows >> Extension >> AtomX.

2. Drag and Drop files *.atom in the package into extension.