Its bootable USB sticks still don't work.
Disk / partition image backup apps really aren't that complicated if you ignore any optional features, e.g., Macrium Reflect's devs have likely invested significant work developing its data transfer methods. If you take a page full of text and delete all the white space, between words, paragraphs etc., you no longer have a full page of text. At a very basic level that's how zipping several files into one .zip file works. And that's also the principle behind disk / partition image backups. You copy *just* the data -- no *white* space -- to a virtual hard disk, which is usually a single file a bit smaller than the amount of space actually used on the original partition(s). To restore a backup you copy that data somewhere else, e.g., a physical hard disk, where the white space is restored. You won't save much if any space zipping some file types -- the GOTD games are a good example -- and you won't save any space backing up some types of files, e.g., video or .vhd, because they don't contain much if any *white* space. Most image backup apps also let you mount the virtual hard disks their archives are stored in, so they appear in File Explorer just like the original partition they were created from -- that allows you to copy any & all files &/or folders to another disk partition.
When you're using a PC/laptop you're also using an OS [Operating System], as that's what makes the PC/laptop more than just a collection of electronic parts. Every OS uses files, and you can't mess with them while they're in use -- otherwise the OS would crash because it was prevented from using one or more of its files. Windows can make a virtual copy of running files [VSS], and those copies are what is stored in an image backup. You can't reverse the process however. To restore a backup that contains an OS, that OS cannot be running, so you have to run a separate copy of that or a different OS, and run the backup software from that copy. And the target disk, where you want to restore the backup, must be connected, along with a drive where the backup archive is stored.
Personally, on our PCs, where we have extra storage space, I have a 2nd copy of Windows installed, without any software other than 7Zip & the backup app. It uses the same activation as the primary copy of Windows, so no extra cost, can act as a spare if the primary copy is acting up or broken, and makes backup/restore, as well as many maintenance & repair procedures as easy as possible.
In practice you can physically attach the target drive to another PC/laptop, e.g., using a USB drive dock, to perform either a backup or restore. You can install the backup software to a Windows To Go drive [i.e., a full copy of Windows on a USB stick/drive], and boot the PC/laptop to that, then run the backup software. And most image backup apps let you create a bootable ISO or USB stick with a usually minimal copy of an OS and of the backup software, and many will let you write that same minimal OS & app to a hard disk in your PC/laptop. Functionally there should be little to no difference between the two -- the USB stick may be slower, while the copy added to your hard disk may screw up Windows boot loader files. At any rate, that's where Backupper fails.
AOMEI's bootable USB sticks may have been broken for approaching a decade -- I tested them in 2014, then again starting late last year [& every version since], so I don't know whether they fixed them and then broke them again. Maybe most of their customers use older hardware booting to legacy BIOS? Maybe most never even try to see if the bootable USB sticks work with their PC/laptop? Macrium Reflect is a great alternative, but it's pricey. O&O DiskImage Pro is comparable to Macrium Reflect but MUCH cheaper. DiskGenius has free & paid versions that are also available in a portable version, and it also does partitions and file recovery, though the GUI may be confusing. All 3 can create bootable USB sticks that work.