Jonathan,
When I go there it seems to be asking for a password. I don't
recall ever setting any passwords.
You might not have. You can log in by clicking "Email me a link to log in" and never bother to set a password. The emailed link will log you in for 30 days.
How do I find out what this is?
There's no way to find out what your password is. You can set one (or reset it) using the emailed log-in link, as above, or by clicking the "Forgot your password?" link.
So does every member of the list need to set their timezone?
Yes. I thought that the timezone was automatically detected when each user first logs in, or maybe the first time they post. But maybe not. And it wouldn't help a digest user who hasn't logged in or posted yet anyway.
Shal
Shal Farley