i had a case once (avoton system) where installing failed but running from a installed usb/disk combination worked
i'd try that that 1.03b usb and one of the disks you want to use in a different hardware, if the usb is ok then it should work on a different hardware, after installing move both to your C2538 system and see if it boots
i never found out why it was not installing, you would need to connect a serial (null modem) cable to find out whats going on and even then you might not want to dig in that deep into the synology install process, much easier to try to "skip" install and doing this step on a different hardware
also to spare some update trouble you might start with the latest 6.2.2 version (there are matching drives available now)
https://xpenology.com/forum/topic/21663-driver-extension-jun-103b104b-for-dsm622-for-3615xs-3617xs-918/