Magento 1 Reviews Plugin Installation Guide
Log in to your Magento Account
Navigate to System >> Magento Connect >> Magento Connect Manager
Copy and paste the following extension key as shown in Fig 1 into the "Paste extension key to install"
Click Install and wait for the process to complete
Click on Return to Admin
Log out of Magento Admin and then log back in.
It's important to log out and log back in to Magento after Step 5 to avoid a 404 error.
In Magento, navigate to Reviews > Setup
Enter your API Credentials as shown in Fig 2.
Store ID: [YOUR STORE ID HERE]
API Key: [YOUR API KEY HERE]