Some users faced such issues a while ago, but we were able to fix them. I recommend you try again after clearing the browser's cache and cookies or working with a different browser to see if that makes any difference.
Still, if you encounter the issue, please refer to https://adobe.ly/3RSg2gh and share the.HAR files with us, so we can work on resolving it.
Also, let us know if:
You can log in and access Express by using an incognito browser window or try logging out and then back in on a different browser after clearing the cache/cookies.
Whether you can log in and use other Adobe services, for example, to the Creative Cloud home page https://adobe.ly/4cnKSpf