Problemas con modal

Estoy intentando copiar este ejemplo: https://mdbootstrap.com/javascript/modals/ en mi proyecto con pug, osea intento imitar el modal asi que lo he copiado y pegado, pero resulta que el modal me queda debaj, en vez de salirme cuando toque el boton, aca mi pug:

Código:

doctype html
html
	head
		title=title
		meta(charset='utf-8')
		meta(name='viewport', content='width=device-width, initial-scale=1, shrink-to-fit=no')
		script(src='https://code.jquery.com/jquery-3.2.1.slim.min.js', integrity='sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN', crossorigin='anonymous')
		link(href='https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css', rel='stylesheet')
		link(href='https://cdnjs.cloudflare.com/ajax/libs/mdbootstrap/4.4.5/css/mdb.min.css', rel='stylesheet')
		link(href='css/style.css', rel='stylesheet')
		script(src='js/main.js')
	body
		block content

Código:

extends layout
block content
	.view.hm-black-light
		.full-bg-img.flex-center
			ul.animated.fadeInUp
				li
					h1.display-3.b-4.font-bold Grapict
				li
					h3.mb-5 See the posts you really want to see
				li
					button.btn.btn-primary(type='button', data-toggle='modal', data-target='#register') Launch demo modal

	#register.modal.fade(tabindex='-1', role='dialog', aria-labelledby='exampleModalLabel', aria-hidden='true')
	.modal-dialog.modal-side.modal-top-right(role='document')
		.modal-content
			.modal-header
				h5#exampleModalLabel.modal-title Modal title
				button.close(type='button', data-dismiss='modal', aria-label='Close')
					span(aria-hidden='true') ×
			.modal-body
				| ...

	script(src='https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js', integrity='sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl', crossorigin='anonymous')
	script(src='https://cdnjs.cloudflare.com/ajax/libs/mdbootstrap/4.4.5/js/mdb.min.js')

todo bien, peor el modal me sale debajo, no deberia ser asi, deberia de salirme cuando le de clic al boton.

tengo el codigo aca corriendo: https://afternoon-temple-14236.herokuapp.com/