To build the under construction page for wish, you need to first import the Under Construction slider into your revolution slider page like this:
And choose the under construction slider you downloaded.
After you have imported the slider, you need to add a new page and add the under construction slider into that page using visual composer revolution slider element:
After publishing the page you can enable the under construction mode (if you need to) from the theme settings page in the troubleshooting tab:
You also need to choose the “Under Construction” page you just created and the date when the site comes back live in the same tab.
Now all the non-logged in users will see the under construction page on all the site. The admin and other users can still sign-in using /wp-admin page.