In order to install the extension using FTP client, you need to unzip the package file and upload contents of ‘upload’ folder to the root folder of your store (figure 1)
Figure 1. FTP client
The next thing to do is to import modifications to OpenCart installation. The simplest way is to use OpenCart Extension Installer. To do it upload file adk_mail.ocmod.xml from the package root using Extension Installer (figure 2).
Figure 2. OCMOD modification import
If you have previously installed modification for that module you need to remove it at ‘Extensions > Modifications’ page. After successful installation, you need to refresh the modifications at the Modifications page.
If for some reason you cannot use OpenCart Extension Installer but you have VQMOD installed in your store then upload file adk_mail.vqmod.xml from the package root to /vqmod/xml/ folder of your store (figure 3)
Figure 3. VQMOD modification import
If OpenCart Extension Installer doesn’t work properly on your OpenCart installation and you don’t have VQMOD in your system you still can import extension’s modifications. To do it copy file adk_mail.ocmod.xml from the package root to system/ folder of your store (figure 4). After that, you need to refresh modifications at Modifications page. Also, you need to remember that when you decide to remove the extension you need to remove that modification file as well and if later you’ll import extension’s modifications via OpenCart Extension Installer or VQMOD you need to delete the modification file from system/ folder as well since failing to do it will lead to doubling extension’s modifications and possibly to errors in your OpenCart installation
Figure 4. Direct import of OCMOD modifications