This article explains how to create a new VKontakte custom App and obtain the right permissions to use it.
How to create the custom VKontakte APP
STEP 1
Go to https://vk.com/dev and login
STEP 2
Click on "My apps"

and then on "Create an Application"

STEP 3
Select the category "Website". Then provide the name of your Application, the site address in this format
https://splash.YOURDOMAIN.com
and your base domain replacing YOURDOMAIN with your current domain.
Click on "Connect Site" to crate the APP.

You will be required to confirm your request with a code send via SMS to your mobile phone number.

The procedure should be completed in max 60 seconds.
STEP 4
On the left, click on "Settings", and write down the Application ID (Client ID) and the Secure Key (Client Secret).
Those two information need to be set in White Label Splash Editor.

Related Article:
How to configure the Tanaza Splash Page to work with your custom app