you should really use a test account when experimenting with random matrix clients. meanwhile we’re looking at adding OAuth 2 to Matrix by default so your server is the one that auths you, rather than a random client: https://github.com/matrix-org/matrix-doc/pull/2964#issuecomm...
Then I'm guessing it has a captcha. I'm not sure because it fails to load with Privacy Badger enabled.
My attention just wandered away. Hopefully they can address some basic privacy concerns and get another at-bat.
Edit: Seems that matrix.org is now requiring an email address.