A buck LED driver will have a very specific voltage range. With a max and min Vf. LED CC drivers are sold by their wattage and max voltage.
For example this is a Mean Well 120 Watt driver available in various voltages. Each voltage model has a range of Vf supported.
None of which will work for you becasue your Vf is too low. The 12V min is 6V.
A higher Vf is usually more efficient. It also helps to use a Vin not too far over the Vf.
What would be your Vf if you wired all the LEDs in series?
I limit the string voltages to less than 48V. typicality 16 in series for white, blue and green, and 21 in series for red, orange, and yellow.
I NEVER power two parallel multiple LED strings with a CC driver. I have tried many times with various string and never did the current balance between the two strings. Closest was a 45/55 split.
I am using a buck and a cheapo power supply
When all the LEDs have the same Vf and the desired current is constant, a CV supply and resistors can be an excellent solution. With the correct constant voltage you can get better than 98% efficiency from the resistors. It depends upon how closely you need the radiance or irradiance of each LED to match. Even with the same current flowing there will be a variance in output intensity between each LED.
This would probably work better if you had 8 sets of 5.6V pairs all wired in series for a total string Vf of 44.8. You then use a 48V CV supply and a 4.3 Ω 4W resistor for a minimum efficiency of 94%. With a good CV source you can adjust the output voltage and resistor value for even better efficiency.
If you were to use a 5.7 V CV source and 5.6 Vf. This would require measuring the Vf of the LEDs at 700 mA after they reach thermal equilibrium to calculate the resistor. And use quality LEDs from a manufacturer that specifies the min and max Vf where the range is not too large.
Running all LEDs in a single string with a singe CC source, is generally the best way to go when you want the same brightness from each LED.
In some projects I use an inexpensive 48V CC driver made with a TI LM3414HV tweaked to 97% efficiency (switching freq. and inductance) powered with a stable high efficiency CV source like a Mean Well HEP at 96% efficiency. Each driver powers a sting of 16 white or blue or 21 red for horticulture projects. I need current adjustment as the plants grow so resistors will not work well in most projects.