Method 1: Theme Installation Via Admin Panel

First of all, you need to download the theme installable file from your account that purchased item, go to your ThemeForest Account > Downloads Tab

Now go to your site Dashboard > Appearance > Themes and click on Add New Theme like below

Now click on Upload Theme

Choose the zipped file that you have Downloaded from ThemeForest and click on the Install button, then wait for the installation process

Final step click on Activate theme

Method 2: Theme Installation Via FTP

If you can’t install the theme via method 1, So try this way:

• Log in to your server via your FTP software ( FileZilla, Transmit, etc )
• Unzip the oppi.zip file, ONLY use the extracted theme folder.
• Upload the extracted theme folder into wp-content > themes
• Activate the newly installed theme by going to Appearance > Themes
• Go to Appearance > Install Plugins and install all required plugins
• Simply click the Install button on each plugin to install them
• Done