You need to connect them as
four cells in series; that's where the 16.8V comes from.
Then another chain of four in series, wired in parallel with the first. The voltage stays the same, but the AH capacity and current ratings are double, as the load is shared between the two sets.
It's abbreviated to 4S2P (or 2P4S) configuration; four cells series, two sets of cells parallel.
Like this, but hopefully with a much higher rated BMS module than in the picture...