Is your site made with wordpress? My is and I had to take extra steps to make it work. For example your link that you provided need the property ID included to make it work. Think you need to got to beds24, log in, go to settings, go to booking engine, go to booking widgets, see the page that says widget desginer at the top, go to bottom of the page and you can see a sample and click wordpress short code (orange box). You will see a code that looks like this :[bookwidget propid=53190 formAction=’https://beds24.com/booking.php’ widgetLang=’en’ widgetType=’BookingBox’]
Your property ID will show up like mine above. I copied and pasted the code above on my bed and breakfast inn page at the top of each page. Good luck! I am not a computer expert, just an innkeeper/owner, just played with it for awile until it worked for me.