A quorum is the minimum number of members of an organisation who must be present in order for their meeting to be legal or official.
Most legislation and or organisation constitutions set what the number of members is for a meeting to be conducted.
In BoardPro you can set this number under Organisations -->Automation
BoardPro automatically sets the number at 50% but use the up and down arrows next to the number field to set the correct number for your organisation.
Depending upon what the percentage is on the Voting Automation tab, if the quorum is not met, you will receive an alert above the Attendee's list on the Meeting Details Page.