Harlow had the better of the first half but fell behind to a volley by Jack Leachman (pictured) in the 41st minute.
The visitors then looked the more dangerous side after the break but could not add to their score.
Harlow's Mitchell Das had to be stretchered off after a strong challenge by Manny Sackey. That led to a lengthy period of added time and Brown squared it in the 96th minute from a cross by Ben Hart.
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