Hi Umiumansa,
Bubble does not support a max height for the page by default, but there are (at least) 2 solutions:
1) Using CSS
Set the id attribute for the page. For the element with that attribute set the height using CSS (to 100vh !important):

2) Using a Floating Group
Settings Group Header:
Settings FloatingGroup Body:
Note: The top margin set to 80px to display the header
Settings Group Left & Right:
Now when there is content (the grey group in the example below) with a height that exceeds the height of Group Left, this last group becomes scrollable:

Hope it helps!