ERROR: failed to create default 1024

Hey,

I'm very new to this and just tried to install sophos for the first time (sophos xg home) on and old htpc of mine.
My configuration is as follows:

Motherboard: ASRock B85M-ITX
CPU: Intel Core i3 4130T
RAM: 8GB DDR3 (2x4GB)
SSD: 120Gb
NIC: 4-port gigabit HP network card

I downloaded the latest ISO and made a bootable usb (first via rufus, later through etcher) and tried to start the install. I get the confirmation screen to ask if its the correct drive and such, however, after that it errors out with the following error:

Completed: [ == 1%]

Formating Configuration Partition losetup: invalid number '/conf'

sh: 0: unknown operand

ERROR: failed to create default 1024,

ERROR configuring partitions

Aborting

press y to reboot.

Is there anyone who might know what to do to get it working?