Thanks @SeanHatfield for your answer.
I'm not allowed to use "administrator@vsphere.local" account (for security concerns) but I have full right so I created other local admin account on the local SSO domain (the "vsphere.local" one) with the same result as with a more "classical" account (an Active directory integrated one). I've added this local account to the "administrators" group (and with the full Admin role) so this user is able to do anything on the host (and vcenter) . I've manually tested to deploy a VM from a custom ovf template, with success.
As I wanted to test a fully supported solution (before to buy it) I had not tried to deploy Ontap Select from OVF version. But as you've asked for it, I've done the test, and installed "ONTAP® Select 9.3RC1 Evaluation OVF Template" (from ontap evaluation software page).
With this OVF template, i've successfully been able to deploy single node by using the local admin account mentionned above, on a local DAS datastore (the one tested with Ontap Deploy) and also on a SAN shared storage datastore (the one tested with Ontap Deploy).
Here is the screenshot of the successfull local DAS storage Ontap Select deployment just after successfull deployment (without any modification in system manager):

And here is the snapshot of the successfull deployment on the SAN Datastore just after successfull deployment (without any modification in system manager):

I also checked at VM configuration after OVF deployment and there are some differences with OnTap Deploy deployment :
- 3 vnic (all in same PG) with OVF vs 6 vnics (all in same PG) with Ontap Deploy
- 4 vdisks with OVF vs 1 vdisk with Ontap Deploy
Conclusion
1. It is technically better than before, as I've got a successfully deployed single node cluster 🙂
2. but I can not really test further the node deployed this way as it is an unsupported solution 😞
Regards.
Pierre.