After installing the extension for Magento 1, you need to set up the Cron Settings for Magento in case it is not there, so that it enables the set of actions to take place after a particular time interval.

Various Magento features need at least one Cron job to schedule the activities in future. Some of those activities are:

• Catalog Price Rules
• Newsletters
• Generating Google sitemaps
• Customer Alerts/Notifications (product price change, product back in stock)
• Reindexing
• Private sales (Magento Commerce only)
• Automatic updating of currency rates
• All Magento e-mails (including order confirmation and transactional)

How to do that?

To create a cron job as the user who runs Apache, the following commands in the order shown:

1. Create or edit a crontab for the Apache user:

   crontab -u apache-user-name -e

2. A text editor displays. (You might need to choose a text editor first.)
   In the editor, enter the following:

   * * * * * /bin/sh /[your Magento install dir]/cron.sh

   For example, for CentOS,

   * * * * *  /bin/sh /var/www/html/magento/cron.sh

3. Save your changes to the crontab and exit the editor.

To know more about it in detail, click here and go through the complete guide to set up Cron Jobs for Magento 1.