You have uploaded product-stock-alert-x.x.x.ocmod.zip via extension installer (Extensions > Installer) successfully, but you cannot find the module under Extensions > Extensions > Modules > Product Stock Alert

Checklist:

• Go to Sytem > Users > User Groups.
• Click on Appropriate User Group (Administrator)
• Find extension/module/hb_oosn (module/hb_oosn for OpenCart 2.2.0.0 and older versions)
• If you do not see this in the list, it means that there is some problem with extension installer failing to copy the files to server. In this case you need to do it manually via File Manager Program or software like filezilla. Follow the solution below

Solution

1. Extract product-stock-alert-x.x.x.ocmod.zip. You will find the upload folder inside it.
2. Access your server via FileZilla and locate your directory where OpenCart is installed.
3. Extract the contents inside the upload folder to your server root directory where OpenCart is installed, such that the folders merge with the existing admin and catalog folder.