This can not be done by means of Muse. You need knowledge of the code. And the Muse in this case is completely unnecessary.
I have to admit it`s less then a quarter . I didn´t realize the right side scrolls as well. Shame on me lazy compromise, though.
Check this, if it can let one side stay: https://www.muse-themes.com/products/multiscroll
Not sure if it completely helps though.
Quick and dirty and with no menu, you could watch out here: Homepage
I put it on and old BC-site which is needed anymore. Download directly from the browser.
There are quite some restrictions, so not everything is possible, left side in your example is responsive in width and height, while my example is responsive in width only. The right side is responsive in width and height. Take care of your examples-non existing footer.
Just check it out.