Beginning in ONTAP 9.4, NVMe/FC is supported. Beginning with ONTAP 9.5 a license is required to support NVMe. If NVMe is enabled in ONTAP 9.4, a 90 day grace period is given to acquire the license after upgrading to ONTAP 9.5.
You can enable the license using the following command:
system license add -license-code NVMe_license_key