SNMP v3 Syntax

Apologies for the entry-level question, but I've been playing with this for a couple of hours now and haven't managed to figure it out.  Would appreciate someone who already knows letting me know where I've gone wrong.

The end-goal is to add my GS324TP switch to my monitoring setup.  The stage I'm at is  trying to perform a simple SMTP walk with SMTP v3.

I can authenticate with SMTP v2 with the following syntax:

To enable this, from the GUI I simply set:

- Management Station IP + mask to the IP + mask of the machine making the SMTP walk

- Community String 'grafana' (referenced in the call)

- Access Mode 'Read Only'

- Status 'Enable'

Moving onto SMTPv3 with no other changes, I read this documentation here:

https://kb.netgear.com/000058234/How-do-I-configure-SNMPv3-users-on-my-NETGEAR-GS728TPv2-GS728TPPv2-GS752TPv2-or-GS752TPP-switch

This seems to suggest that I need to:

- log in with my admin user, using the GUI password

OR:

- create an additional user, who will have read-only access

I created an additional read-only user as follows:

Username - grafana

SNMP Access Mode - Read-Only

Autentication Protocol - SHA512

Authentication Key - password

Encryption Protocol - None

Encryption Key - N/A

I'll add an encryption key once I get a basic connection established.

The syntax that I think should work for this is below:

I've tried several variations on this, but I always come back to the error below:

snmpwalk: Authentication failure (incorrect password, community or key)

I've also tried logging in with the admin user, with the associated GUI password, with and without encapsulating ''s and ""s, with the same result.

I'd very much appreciate someone pointing out my mistake!