Its work for me

{
			module: 'calendar',
			header: 'Icloud Calendar',
			position: 'top_left',
			config: {
				calendars: [
					{
						symbol: 'calendar-check-o ',
						url: 'https://p02-calendars.icloud.com/published/2/xxxxxxxxxxxxxxxxxxxxxQhtoAvoFiIwGI1-5MBbuND5g_96k2kQyqGV90wUFfxxxxxxxxxxx'
					}
				]
			}
		},

Note from admin: Please use Markdown on code snippets for easier reading!

Its work for me

{
			module: 'calendar',
			header: 'Icloud Calendar',
			position: 'top_left',
			config: {
				calendars: [
					{
						symbol: 'calendar-check-o ',
						url: 'https://p02-calendars.icloud.com/published/2/xxxxxxxxxxxxxxxxxxxxxQhtoAvoFiIwGI1-5MBbuND5g_96k2kQyqGV90wUFfxxxxxxxxxxx'
					}
				]
			}
		},

Note from admin: Please use Markdown on code snippets for easier reading!