Ok.... easiest would be to get a power supply that outputs more than the forward voltage of the leds, and then use a couple BUCK led drivers to control the current going through each led, using a potentiometer for each driver. Or you could use a dual potentiometer / stereo potentiometer (but these are logarithmic so the brightness won't change as linearly)
The page says 36-39v forward voltage, up to 600 mA for each led ... but knowing the quality of leds on Aliexpress I'd say don't go over 450-500mA ... anyway.
Example of step-down / buck led drivers :
AL8862 :
https://www.digikey.com/en/products/detail/diodes-incorporated/AL8862QSP-13/10670150max 55v in, 1A 0.4v .. 2.5v on CTRL pin to adjust brightness (so a potentiometer and a resistor to form a voltage divider and you're good.
ILD6150 :
https://www.digikey.com/en/products/detail/infineon-technologies/ILD6150XUMA1/4897530max 60v, 1.5A ... same deal, you can set max current with the Rsense resistor and then use a potentiometer to adjust brightness
Datasheets contain example circuits with values of components, example application circuits..
Let's say you need at least 42v and 1.2A so a total of 50 watts.
Easiest to obtain that would be by either with a 48v power supply (you can adjust the output voltage a bit to bring it down a bit for less losses if needed) or by making your own power supply using a classic transformer.
For example find a toroidal transformer or a classic transformer with two 18-24v AC secondary windings (or a single 36-48v secondary winding), add a bridge rectifier and a big capacitor on the output and you have your 42v+ power supply. If you want to get the full 50w on the led, you'll need at least a 75VA or higher transformer, otherwise you could go with a 50 VA transformer (and expect maybe 400mA on each led, still quite bright)
Here's some examples :
50w toroidal for 18$
https://www.aliexpress.com/item/1005004459527878.html100w toroidal for 28$
https://www.aliexpress.com/item/1005004459735891.htmlA bridge rectifier converts AC voltage to DC voltage, and result is a DC voltage with a peak equal to Vdc peak = 1.414 x Vac - 2 x voltage drop on rectifier diodes.
So for example, with 18v AC secondary windings for a total of 36v AC you would get Vdc peak = 1.414 x 36v - ~ 2v = 49v DC peak.
Now you determine how big of a capacitor to use to keep the minimum voltage always above some threshold, let's say 42v in our case ...
C = Current / ( 2 x AC frequency x (Vdc peak - Vdc min) ) = 1.2 A / 2 x 60 x (49 - 42) = 1.2 / 120x7 = 0.00142857 Farads or 1428.6 uF ... so you'd need at least a 1500uF 63v rated capacitor to keep the voltage above 42v all the time. I'd use 2200-3300uF.