How to open external link in popup?

Hi guys,

I need external link (containing only a simple booking calendar – https://bit.ly/2qehQ3S ) – to be opened in a popup on my web page.

I tried like this – in “text” tab of popup:
<iframe src=”https://booking.rentl.io/en/6915/1726a55b-8f7a-460a-ba90-383bb98de340&#8243; width=”300″ height=”500″></iframe>

with this on page:

But it doesnt work; How do I set it up?

Thanks and have a great day!