One problem with you formula is that the url is enclosed between < and >, remove these characters.
Regarding your function, the arguments in masterCal.createAllDayEvent(title, location, description,date) have not being declared.
You could save a lot of time while writing your scripts / fixing them by following the recommendations of https://...
Another option (an expansion of this answer ...
1. Select A10:A20 > right click > Data Validation
Criteria = "List from range" > F2
2. Formula in cell F2: =mult(now(),1) " )
Is to create two cells, one with a tick box option (A3), and the one next to it (B3) with the "list from range" validation.
If you do that, then whenever you tick the box ...