iframe doesn't load

Hi,

The IFRAME doesn’t load in the below website
http://www.theparlournolita.com/index/book-online-now

I have used the original code from the developer

<iframe src="https://theparlournolita.phorest.me/book" width="900" height="900" frameborder="0"></iframe>

and with your short code as well —————

[iframe src="https://theparlournolita.phorest.me/book" width="100%" height="500"]

Any advices?
Thanks

https://ww.wp.xz.cn/plugins/iframe/