Modify the output voltage on a PWM controller to fall within LED driver range
The easiest way would be to use a transistor to pull the PWM-Dim pin down to PWM-.
The PWM-Dim is also the on/off signal for the power supply.  Open (no connected, floating) is on.  Connected to PWM- is off.  That means it has a pull up connected internally.  All you have to do is pull down PWM-Dim.
Your PWM controller provides up to 5A of current, and is complete overkill.  You can still use it.
Here's how I'd go about it:



simulate this circuit &ndash; Schematic created using CircuitLab
It has the disadvantage that the dimmer knob on your PWM controller will work backwards.  This circuit inverts the PWM signal.  When the PWM controller generates a 1% duty cycle, the LDH45 will receive a 99% duty cycle. When the PWM controller generates a 90% duty cycle, the LDH45 will receive a 10% duty cycle.