I ended up figuring it out. All I had to do was create a form in one of my react components and pass the auth0 user id to it and since it was on the front end it had access to the useUser hook
<form method="POST" action="/api/create_customer_portal_session">
<input type={'hidden'} name={'customerID'} value={customerID} onChange={() => {}}/>
<button type="submit">Account Settings</button>
</form>
I had no idea I could pass a hidden value to an input. But, it worked out and everything is linked correctly now!