Related to the limitations for the BigBlueButton test server I found the next info: https://moodle.org/mod/forum/discuss.php?d=352068#p1420723, please see my questions in bold...
1- anyone can access your sessions at anytime (does that means that my recordings are available to anyone in internet?)
2- it can be used by everybody which means that there may be cases when the maximum capacity is reached (Anyone is using the free version and could share if there are a lot problems with it?)
3- its recordings will last only for 14 days.
4- the administrators could shut it down any time. We don't do that, and we do our best to keep it up and running, but sometimes maintenance interruptions (Anyone using it could share here is there are problems often?)
5. It seems as there is not limit in users a long a the test server is not overused at a certain moment: https://groups.google.com/g/bigbluebutton-espanol/c/b9x1QRaSfDA?pli=1 anyone konws if this info is correct?
Thanks a lot for any help!