JOTA and GONGOMGRA helped me to set up the Bitnami Roundcube App on my Mac OSX machine running Catalina. It took some time but eventually I failed to understand that the Roundcube App developed by Bitnami was developed to support local work groups on a cloud based platform. I downloaded and printed the current Bitnami Whitepaper and am still studying this document. That is why I was never able to get Bitnami Roundcube App to work. Apple, a trillion dollar company, has deprecated the Mac OSX Server App to the point of eliminating both email and https websites. Apple claims that the owner of the server is better off installing the service on the server themselves without the help of the Mac Server App which is abbreviated at best. Which means that the software can't be upgraded when the updates are published by Apache or Roundcube, etc.
My server is not a cloud based server nor an intranet and is reachable over the WWW. I have been running a Coldfusion Website and server side scripting successfully for quite a while. I can no longer run Coldfusion as there is no suitable platform for a website as mentioned.
It would appear that I must install Roundcube and Apache on my server myself. Apache is already running but not configured for secure https which is needed for Coldfusion. As well, Roundcube is downloaded from Roundcube.net but has already been updated by Roundcube(1.4.9) and is not running on my server successfully. What does work is backed up on an older Mac running previous versions of Mac Server. If you try to contact Roundcube.net for support you will get no response. At least in my experience. The larger companies can afford to have this type of work outsourced. I won't have the engineers at Bitnami to help me but my server has always been the best value for such services. If you know of a better plan of attack I would consider this helpful. Github appears to have a good installation guide for Roundcube so far. Thx, Ted C.