On 23 Nov 2022, g00r00 said the following...
 
 g0>  LM> No more Upgrade to alpha of mystic ?
 g0>  LM> http://www.mysticbbs.com/downloads/prealpha/   NO MORE ACCESS
 g0>  LM> 
 g0>  LM> Does its Support ? or EOL
 g0> 
 g0> Not sure, I don't manage mysticbbs.com its probably just a temporary
 g0> quirk.

I confirm it's the same for me too, looks like folder listing is now not allowed on that web directory.
I get this now:

It appears you don't have
permission to access this page.
403 Error. Forbidden.

--- Mystic BBS v1.12 A48 2022/07/15 (Linux/64)