The Progressive Web App flavor of HCL Verse does not sync with / subscribe to external calendars. This is only available on the Mobile version. And while Verse does offer users the ability to import calendars, this functionality is highly limited in that it does not process updates automatically, i.e. new events, reschedules, etc.
It is a common feature for calendar apps to integrate. Outlook provides such functionality, as well as Google & Apple Calendars. Being able to subscribe and have Verse events visible in other calendars, and vice versa, would be great to see, and prevent a lot of hassle having to check multiple calendars.