Samsung Electronics GmbH
Hello,
Thank you for your enquiry.
The Samsung SSD 970 EVO Plus is not compatible with the iMac (Retina 4K, 21.5, 2017 - iMac18.2).
This SSD can be used if the motherboard has an M.2 slot. To use the full performance of the SSD, the M.2 slot should have PCIe 3.0 with 4 lanes.
Alternatively, we recommend the Samsung 870 QVO, 870 EVO, 860 PRO.
If in doubt, please enquire directly with Apple support.
Kind regards from Schwalbach
Your Samsung Service Team