Method 1: Theme Installation Via Admin Panel
Step 1.. First of all, you need to download the installable theme file from the account that purchased the item, go to your ThemeForest Account > Downloads

Step 2.. Now go to your site Dashboard > Appearance > Themes and click on Add New Theme like below

Step 3.. Now click on Upload Theme

Step 4.. Choose the zipped file that you have Downloaded from ThemeForest and click on Install , then wait for the installation process

Step 5.. Final step click on Activate theme

Method 2: Theme Installation Via FTP
If you can’t install the theme via method 1, try this method:
- Log in to your server via your FTP software ( FileZilla, Transmit, etc )
- Unzip the Apppay.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