Add authorization with VKontakte to the site on the Belloo engine (4.2.7).
The receipt and display of data of the visitor who has pressed the "Auth with VKontakte" button has already been arranged ([login to view URL])
It is necessary to send them to the database (by implementing the registration of a new user, the login of a previously registered one) by analogy with the existing Google and Facebook. Apparently having corrected 2 files (/assets/sources/[login to view URL] and /assets/includes/core.php. I think that you don't need to know the features (specifics) of the engine for this. Just a little something to do following the example of those available for google, facebook, twitter or instagram. Just understand these tricky words-variables. Let's check the functionality on the desktop and mobile version.
I think it will take a specialist 10 minutes
A detailed manual is needed, what was done, because after the engine updates are coming, it may be necessary to "correct" the files that are batch replaced during these updates.