Never do anything directly on a live store. First setup and test on a development domain (i.e. “dev.url.com”).
Temporarily disable Magento cache
To avoid any possible issues with the installation we recommend disabling Magento cache before proceeding with the installation and re-enabling it once the install is complete.
Upload PO Box extension Files
Using your favorite FTP client, upload all files and folders to the root folder of your Magento installation
Once again, thank you so much for purchasing this extension, I'd be glad to help you if you have any questions relating to this extension. No guarantees, but I'll do my best to assist