The crowds at both their games I saw in the wilderness tears were lower than Broncos average last season by a bit. It depends on which part of their journey you saw them tbh.
If Wikipedia is to be trusted 1993 - 2011 they played at 4 grounds. The highest attendance was as follows:-
Maidstone 320.
Central Park Sittingbourne 412
Bourne Park Sittingbourne 1,729
Ashford 488.
Last time I went there they had a gate of 2,296 (2014.)
The move to Ashford, a horrible place to get to without a car, saw attendances drop badly.