Started with the login function and it works more or less :-)

frontend/src/auth/AuthProvider.js

@@ -0,0 +1,11 @@
+import { createAuthProvider } from "react-token-auth";
+
+export const [useAuth, authFetch, login, logout] = 
+createAuthProvider({
+  accessTokenKey: 'access_token',
+  onUpdateToken: (token) => fetch('/api/refresh', {
+    method: 'POST',
+    body: token.access_token
+  })
+  .then(r => r.json())
+})