How to display Season, Semester, and Cycle of years on Fullcalendar

I'm looking for a calendar that allow me schedule events for all semesters, weeks of semesters,cycle of years and seasons.

As suggested from the Github of Toast Ui, they said to look on full calendar TyperScript. https://github.com/fullcalendar/fullcalendar/issues/6622

but the bot say to ask here so i'm here, there is some easy way to do what i'm trying to achieve, this is a project for a school so this is why i'm trying to get abstract calendar instead of normal calendar.

My goal is to do a Calendar to schedule event and then push to our LMS, our planing, but our staff use abstract date e.g(Semesters,Season,Cycle of Years) i asked to some devs and they put me on the direction of fullcalendar app coded in JavaScript, but when i display this i have this result.

           document.addEventListener('DOMContentLoaded', function() {
              var calendarEl = document.getElementById('calendar');
              var calendar = new FullCalendar.Calendar(calendarEl, {
                headerToolbar: {
                  left: 'prev,next today',
                  center: 'title',
                  right: 'timeGridFourDay,dayGridMonth,timeGridWeek,timeGridDay,listWeek'
                },
                views: {
                        timeGridFourDay: {
                        type: 'dayGridMonth',
                        duration: { week: 15 },
                        buttonText: 'Semeters',
                        weekNumbers: true       }
                    },
                initialDate: '2020-09-12',
                navLinks: true, // can click day/week names to navigate views
                nowIndicator: true,
                weekNumbers: true,
                
                weekNumberCalculation: 'ISO',
          
                editable: true,
                selectable: true,
                dayMaxEvents: true,

but when i try day: 75 it only output me some weeks and not 75 days = 15 Week = 1 Semester

What i want is to display 15 Weeks but in this view type .

I have chosen an 'dayGrid' view, wish allow me to view full weeks for 15Weeks thorught the similar month grid.