Diy 18650 4s battery pack [How to charge, how to build?]
That BMS looks identical to one that I've used and it does NOT do balancing or proper charging.  Just protecting from over current, over voltage and under voltage - all of which are very important.

You will need to add balance wires and get a balance charger for this battery.

Balance wires are easy - they go exactly where the bms wires go - one to each pos and neg of each cell.  The balance charger will have a slot for those wires.

I recommend looking at the IMAX b6 charger because it is the cheapest balance charger I have seen and seems to work reasonably well up to batteries with 6s or less.