Can't add Proxmox user (non-root account)

Hi!

I've
1) added Users Group (e.g. Firm);
2) added users to this group (firm_user1, firm_user2 etc.);
3) created a Resource Pool and gave Administrator permission on this pool to Firm group;
4) logged in as firm_user1.
5) wanted to add some users but... buttons Add Edit Remove on the Users tab are disabled.

Can the non-root user add a new Proxmox users via GUI?


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Best regards, Andrew