you do indeed require a $0 license key to install OnCommand Unified Manager Core - perhaps your reseller better knows this by one of it's former names - "DFM" / "Operations Manager".
Support cannot generate this license key - I suggest you ask your reseller open a non-technical case to get more information. If you get a (non-technical) case # you can post it back here and I can add details to the case notes that will assist them in this process.
Re: licensing for Netapp Oncommand Unified Manager Core
OnCommand Unified Manager is an off-box management software product; that is, it runs on a separate server from the storage system, and it does not automatically come on the NetApp storage system or in Data ONTAP. The software is available through the NetApp Support (formerly NOW®) site (https://support.netapp.com/NOW/cgi-bin/software/).
There are two components: OnCommand Unified Manager Core Package and OnCommand Unified Manager Host Package.
OnCommand System Manager software, both the Core and Host Packages, is a no-cost option for customers who have purchased NetApp FAS or V-Series hardware. System Manager is an unlicensed application and is free to download, install, and use. However, depending on the platform model, some features require license keys, you require storage system software licenses to enable certain services and features on your storage system, such as NFS. A license key enables you to unlock and use a single product or multiple products.
There is a potential cost associated with using the Host Package. When using the backup or restore capability of the Host Package for a VMware environment, the customer should get a license for the Virtual Storage Console (formerly known as SnapManager for Virtual Infrastructure). There are two ways in which this can be licensed: as a traditional standalone SMVI server license or through the SnapManager Suite or the Complete Bundle, where FAS/V3200 and FAS/V6200 series systems are involved.
License keys are provided on a per-system basis and must be added on each system for features to work correctly. Some features do not require individual license keys; they are provided free of cost or along with other features when you install a license key for a software pack.
It should be included with SW,Data ONTAP Essentials that was part of the order of the array.
You can find license keys for your initial or add-on software orders at the NetApp Support Site underMy Support > Software Licenses. For instance, you can search with a system’s serial number to
find all license keys for the system, and you can search with a sales order number to find license keys for all systems on the order.
If you cannot locate your license keys from the Software Licenses page, you should contact your sales representative and ask them to process a $0 quote for the OnCommand Server license.