Probably because Wix Users API is not supposed to be used within the Wix Router code setup. That should be used on your own page when you retrieve the router data.
https://support.wix.com/en/article/corvid-creating-a-router
https://support.wix.com/en/article/corvid-about-routers
https://www.wix.com/corvid/reference/wix-router.html
If you view the Stripe example linked below, you can have a good look at using a router with Wix Users.
https://www.wix.com/corvid/forum/community-discussion/example-stripe-payment-processing