Please check that you’re using only 1 memory driver, namely OsxAptioFix2Drv-free2000. You can always experiment with others later, but for initial install, use this one along with “slide=0”.
Also delete “Install MacOS Mojave” from your Mac’s Applications folder and re-download it from the Mac App Store.
Then check whether your USB flash disk is a good name brand product between 8GB and 64GB, preferably 16 to 32 GB.
Reformat the USB flash disk and run UniBeast again.
If the previous Mac installer was corrupt, it makes sense to recheck the very basics of the download and the USB install disk.
Then for extra prudence, remove two of the memory DIMMs, but refer to Designare manual for instructions on which slots to populate when only 2 DIMMs are used.