Hi garretbaily,
The analog input guide is a good place to start (https://www.audesseinc.com/resources/analog-input-guide/).
The input voltages are scaled down to the MCU voltage level though internal circuitry. When it says that the voltage range is 0-36V it means that you can supply the analog input with any voltage in that range and you will be able to read it. Any voltage higher than 36 V will read 36, and you won’t be able to read any negative voltages.
Note that there is some non-linearity past about 30V on the readings.
Please reach out if you have any other questions.