You will find multiple options to add calendars. All with essentially the same process. In this case, to add the calendar of someone working with Huse Culinary click "add from Directory"
You will want to select your "huseculinary.com account"
Then type the name of the person whose calendar you want to add
Once you have selected that person, you will have the option to choose which calendar you want to add to. Ideally, you would want to choose People's calendar.