adding users to WordPress base from Mailchimp subscribers

I run a multisite installation of WordPress and tried to sync from Mailchimp list of Subscribers to subsite koimania.matia.info (mapped as http://www.koimania.cz)
I’m not sure this functionality is supported, but I want to sync (create) users subscribed to Mailchimp back to WordPress user base. I set the hook

http://www.koimania.cz/mc4wp-sync-api/webhook-listener

in my Mailchimp account under Settings/Webhooks and ran the Syncronise All from Mailchimp Sync plugin for that associated Mailchimp list. Unfortunately it did not add the Subscribers created in tha Mailchimp list to WordPress.

https://ww.wp.xz.cn/plugins/mailchimp-sync/