Created a subdomain via Multisite but the URL doesn't work

I'm in the process of converting my website into a Multisite to offer my subscribers their own Wordpress sites. My hosting provider assured me that Wildcard DNS has been activated, so it shouldn't be a problem.
I created a site to test. It sent the e-mail with username, password, etc. But when clicking on the link, it gives an error message saying Google can't find it.
The site shows up in my list of sites and on my Network Admin but trying to use the Dashboard or edit gives the same error message.
Where did I go wrong?