Sorry … should have never switched to German. (English forum)
But you sadly got the wrong devices (hence my links to the migration compatibility checker)
If you had gotten a x86/ARM NAS that checks as compatible in the above tool, then you could do the migration.
The TR is a DAS and if you set it to any RAID mode it will kill the content of the disks, in JBOD/port multiplier mode it will leave the disks alone, but the QNAP cannot boot the OS from an external DAS (yes the OS is on the disks) or assemble the RAID from it.