how to restrict supplier portal contact from assigning a specific role to another supplier contact

Summary:

I went through these documents. Both mention "Allow Supplier to Provision" checkbox but I cannot see it in my instance. can you please provide a screenshot of the task where i can see this checkbox?

1. Document 2170134.1
2. Manage Supplier User Roles

The checkbox that I am talking about is highlighted in this community question, but i cannot see this column in my instance:

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