Cloning is not a backup. You don't restore from a clone. You transfer from drive A to drive B with a clone, but it is not a restore or backup. It's a move, in real time, from one good drive to another good drive---typically when you have run out of space and must buy another drive.
Imaging may be what you are thinking of. That is a backup and is a restore--normally after a major problem, such as disk failure or severe Windows issue.
An image is just another file. It takes up space--typically about half of the size of the occupied space on the drive represented by the image. You can put anything else on the same external, providing you have enough space.
I have a 80 GB C drive, with 30 occupied. The images of that partition range from 11 to 15 GB, depending on which app I use to make the image.
You can't boot from the image file. It must be restored to become bootable.
Direct your sights toward imaging if you are thinking about "backup" as the term is normally used.
In all likelihood, you will not need the paid version of Macrium. The free version is excellent.