You can install this extension via the default Extension Manager of the Joomla Backend, just need to follow the steps below:
First of all, you need to login to your Joomla! admininstrator page. Log-in there with Super-user account to access the installation area.
After you logged in, go to Extensions/Extension Manager/Install. Click on the Browse button and choose the previously downloaded installation package, called VerticalMenu.zip. When you get that, just click on the Upload and install button.
After a few seconds, you should see a welcome message about the successful installation. If there was any error during installation or got a warning message, please check the TroubleShooting part below.
If you got error or warning messages during the installation, you should make sure that the extension working properly, or not. If you experienced a malfunction in the module manager, please contact us on our support page: Offlajn Support Page.