[@Rafa3L]

Код:

procedure HTTP2Work(ASender: TObject; AWorkMode: TWorkMode;
AWorkCount: Int64);
begin 
 ProgressBar.Position:= AWorkCount;
end;

procedure HTTP2WorkBegin(ASender: TObject; AWorkMode: TWorkMode;
AWorkCountMax: Int64);
begin 
 ProgressBar.Position:= 0; 
 ProgressBar.Max:= AWorkcountMax;
end;