A client needs a custom quicklink, which only managers can launch, in order to launch...

The statement is incorrect. The " For Others " option in the quicklink configuration is used to allow users to perform actions on behalf of other identities (e.g., a manager performing an action for a subordinate). However, setting the quicklink to " For Others " does not make it launch a workflow immediately. To have a quicklink launch a workflow immediately when clicked, you would typically need to configure the quicklink to call the workflow directly, without requiring additional user input. " For Others " is more about the context of the action rather than triggering workflows automatically.

SailPoint IdentityIQ Quicklink Development Guide

SailPoint IdentityIQ Administration Guide (Quicklink and Workflow Configuration)