Step 2) Install and Active Polylang or WPML plugin
Read documentation in 2 plugins.
Step 3) Install Multi Language Add-on Plugin.
At the root folder of the downloaded zip from CodeCanyon you will find a zip file (ovabookpro-language.zip) that can be installed on your WordPress site. This file contains the plugin core files. After you've located this file you can start the installation of the plugin.
First, go to Plugins page and click the Add New Plugin button.
Click the Upload link.
Click the Choose File and then, select the ovabookpro-language.zip file.
Finally, activate the plugin by clicking on the Activate Plugin link
II) Update The plugin
1) Auto Update
Use Envato Market WordPress Plugin to automatically update