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}}

• Template:User admin Wikicommons - A similar template for Commons administrators.
• Template:User Commons - A similar template with "the" preceding "Wikimedia Commons"
• Template:User WCUP - A similar template with a short name.
• User:Willscrlt/UBX/UbxWikicommonsUser - A similar template.