The {{User Wikimedia Commons}} template shows that the user is also a user of Wikimedia Commons. It should not be substed. It takes one optional parameter, the name of the user on Commons (only if the user has a different name on Commons). "a page" will never be a redlink due to the nature of cross-project linking, so please check your work by previewing and following the link.
{{User Wikimedia Commons|name on Commons}}
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{{User Wikimedia Commons}}
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{{User Wikimedia Commons|Jimbo Wales}}
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