Here's a video walkthrough of the entire process:
- Open Google Chrome.
- Click the three dots on the Chrome navigation bar.
- Hover your cursor above "Extensions" and click "Visit Chrome Web Store".

- Type "Propel PR" in the search box. Alternatively, you can click this link to directly go to the Propel plug-in page: Gmail plug-in.

- Click the "Add to Chrome" button.

- Click "Add Extension".

- You should get a message saying the plug-in has been installed.

- Open Gmail and log in to your Propel account by clicking the Propel logo.
That's it! You've successfully installed the Gmail plug-in.