Hello Maria,
I tried to access your staging site but the given login details are not working. Please check and send us again. It might be the issue of the cache or plugin conflict issue just because the page builder is not working. I would also suggest you need to purge all the cache from the Autoptimize plugin and then temporarily deactivate the Autoptimize plugin and then check it again. I would also suggest you, please troubleshoot a few common issues.
If it doesn’t work for you please share the correct login details so that we can check it.
Thanks