Unfortunately, there is not a really simple way.
I would not buy an expensive USB-to-SCSI adapter without knowing that it will work.
The design of the Macintosh IIci video circuits makes it difficult to use anything but an old Macintosh monitor with the special 15-pin (two rows) connector in this case (later Macintosh computers could be adapted for use with VGA).
Older Mac computers/monitors/mice/keyboards can sometimes be found in (thrift/charity) second-hand shops.
Do you have an Apple/Mac user group in your area/country?
User Groups - Apple
Once you have access to the SCSI disk and its files via a working pre-1998 Macintosh computer, it would be relatively easy to carry out transfers to a modern Mac or PC. Depending on the old Macintosh model/specifications, there are several methods. Mac- or PC-formatted 1.44 MB diskettes could be used, with a USB floppy drive connected to the modern machine. A serial null-modem or modem-to-modem connection could perhaps be an alternative. If the old (intermediate) Macintosh computer has Ethernet, a network transfer may be used. If it is a pre-1998 PowerBook with PC Card (PCMCIA) slots, a transfer on a CompactFlash memory card would be possible.