Scheduler with authorization through VK?

Question

HTML

Community,
task:
to insert a link to a calendar on the site, where a person can book a time for renting a device.
You can rent a device for at least 30 minutes. and at the same time there are 10 devices.
it is better, of course, to insert the calendar itself with a colored legend, so that you can see whether the day is completely busy or free, or by some percentage.
Environment:
site made on umi.cms free. Most likely it will be moved to another engine.
and so the question is: what is the best way to do this?
VC authorization is required, because the target audience mainly uses VC. other methods of authorization, whether it be twitter, google or just a login-password, are welcome.
maybe there are some inexpensive SaaS? :)

Answer 1

loginza.ru/ from Yandex.
Specifically for UMI CMS:
dev.docs.umi-cms.ru/prakticheskie_primery/podklyuchenie_openid_provajdera_k_forme_avtorizacii/
It is also easy to connect to most engines.
Or, use OpenID authorization PHP modules for your CMS, but there are more problems with them.