EFI System Partition was not found.
It couldn't find the EFI system partition although I am on Win10 64bit with UEFI an secure boot enabled.
secure boot needs to be DIS-abled (unless you can sign the EFI yourself and add the keys to your board).
Secure boot shouldn't affect the installer's ability to find the ESP though.
Well, I surely cannot fix this problem with this information. Can you see the partition in Disk Management? Can you mount the partition on command line with mountvol a: /s?
You can change the boot logo even without going into the EFI system partition. I also couldn't find the EFI location , so what i did was that when the software opens the SPLASH.BMP image , I edited that image into my spidey image with perfection and it worked perfectly .

Please try the new release. If you run into problems during installation, please provide setup.log file for any further assistance.
Closing bugs from obsolete versions. Please reopen if this is still valid for the most recent version.