Other parameters are: Vout = 5V, Iout max = 1.5A.
The 5Vout configuration lists an input voltage range from 6.5V to 40V because the LTM8065 is a step-down uModule. This means it can only make an output voltage lower than the input voltage. The LTM8065 will not be able to output 5V with 4.5V input voltage.
I suggest you look at buck-boost uModules/controllers which have the ability to regulate to an output voltage that is lower or higher than the input voltage.
Buck-Boost Regulators | Analog Devices