First of all, per DGR 18.104.22.168 General (c) Third bullet point, the net quantity indication is not needed for ID 8000 Consumer commodity and Radioactive material.
If the six UN 4G boxes, each being CAO package containing net quantity of 5kg each UN 3090 Li-Metal batteries PI 968 Section IA, are the only packages on the AWB, net quantity marking is not necessary per 22.214.171.124 (c) Second bullet point. However, if the AWB covers both Li-Metal batteries and ID 8000, the Second bullet point does not apply and you must indicate the net quantity of Li-Metal batteries.
If the six UN 4G boxes are overpacked and this is the only shipment on the AWB, the net quantity marking on each of the six UN 4G boxes as well as the net quantity marking on the overpack are not necessary per the Second bullet point. If again, the AWB covers both the Li-Metal battery in an overpack and the package containing ID 8000, the net quantity marking on each of the six UN 4G boxes and on the Li-Metal battery overpack are needed because the Second bullet point do not apply.
Read carefully, as I have explained all the different scenario.