We mean that this application is not present in our catalog, see we don't have specific documentation. You can use the same machine that your Moodle or a different one. Note that Big Blue Button is a Java application, and it usually has high requirements. For example, its documentation says:
The minimum server requirements for installing BigBlueButton 1.1 are
Ubuntu 16.04 64-bit OS
4 GB of memory with swap enabled (8 GB of memory is better)
Quad-core 2.6 GHZ CPU (or faster)
TCP ports 80, 443,and 1935 are accessible
TCP port 7443 is accessible if you intend to configure SSL (recommended), otherwise port 5066 is accessible
UDP ports 16384 - 32768 are accessible
Port 80 is not in use by another application
Note that, in your Moodle instance, port 80 is also used by Moodle, so it should be easier to follow Big Blue Button documentation on a clean instance.
I hope it helps.