Okay all is good just forget I mentioned Rufus
Just so you know a 64gb flash drive is not needed and will be wasted of 63gb's
1gb or 4gb flash drive will work fine the actual system image does not go on it only the small WinPE recovery utility iso which Macrium will download to it and make it bootable for you without doing much at all.
Just open Macrium
On the very top left click on the cd icon it will say Make a recovery media...
I believe CD is selected by default so you'll need to check the box for Flash drive instead but I would personally do both for a backup

The default settings are good so you don't have to change any thing there
The flash drive does have to be formatted as ntfs though so do that before you open Macrium,
Insert the flash drive and click the Start button and click on Computer,
If you see the flash drive listed right click it and click on Format,
It might say Fat32 if it does there will be a drop down next to it to select ntfs then just click on Next/ okay the warning to delete any existing content on it hopefully you don't need anything on it
Once the formatting is done open Macrium and proceed
You can make the recovery media without actually having a system image created so no worries there you can fix WMP later without effecting the recovery media.