Upload the productdownloads.ocmod.zip file from Extensions > Installer. Refresh the Modifications from Extensions > Modifications. Grant Permission to the user groups. Go to Catalog > Product Downloads.You will see the Product Downloads menu. Then Go to Extensions > Modules.You will see the Product Downloads module.Click on Intall. After successful install You can configure the settings as per your requirements.

Extract the zip file.open the 2.3x/2.x folder.Upload admin,catalog folder to your server from the "Upload" folder.
Upload the install.ocmod.xml file from Extension Installer. Refresh the Modifications from Extensions > Modifications. Grant Permission to the user groups. Go to Catalog > Product Downloads.You will see the Product Downloads menu. Then Go to Extensions > Modules.You will see the Product Downloads module.Click on Intall. After successful install You can configure the settings as per your requirements.

Enable the module status. Choose the option accoding to your needs. Add tab heading and description. Add Custom CSS. Create Product Downloads.