Hey Lily, thanks for reaching out!
Events Calendar PRO does not include a separate internal calendar. However, you could create an event category called something like “Internal” and then hide those from the calendar for anyone not logged into WordPress and link directly to that category.
I have to be honest and say that I’m not too sure about integration with Salesforce or SharePoint. I suppose it depends on what sort of integration you are looking for — perhaps you can elaborate a bit more on what you are hoping the calendar will do with each of those and I’d be happy to look into it for you.
Thanks so much!
Geoff