Do my visitors need an account?

No. Someone you send the link to opens it, picks a WOKA and is in the space. No sign-up, no password, no email to confirm. That is deliberate, and it is why sending a link works in seconds.

What anonymous access does not allow

Anonymous users cannot send direct messages or open chat rooms, and they are harder to moderate, since a ban relies on a browser session ID or an IP address. Anyone who wants the full chat experience can register an account from the login page, on their own, if you allow self-registration.

An account is for the people who run the space

You need one to create a map, reach your dashboard and manage members and their rights. Members are added by an administrator and can be granted tags, which control who may enter which rooms and who may moderate. See how can I get my own virtual space?

If you would rather not have an open door

On a paid plan you can require authentication, close self-registration and manage members yourself. See what is the difference between the Free and the paid plans?