Spent some time on this mounting an iSCSI LUN from a NetApp volume.
In your NetApp SVM enter the new initiator with a default name according to the RFQ:



After creating the netapp svm, lun, lif, etc you can mount the new iSCSI volume with the following command.

PS C:\Program Files\Oracle\VirtualBox>
.\VBoxManage.exe storageattach freebsd --storagectl "SATA" --port 0 --type hdd --medium iscsi --server --target "iqn.1992-08.com.netapp:sn.944d91542e4811e8b5b800505600c301:vs.4" --tport 3260 --initiator "iqn.2018-03.freebsd.com:freebsd"  

Here is an screenshot from the Virtual Media Managet (Ctrl-D) in Virtualbox


Now you can go on and install your preferred OS.