How do I get transmission temperature?

In most cases transmission temperature is not readily available in any app. You will need to program the app through 'PIDs' in order to enable it. Some apps require you to have the paid version as well to enable the addition of PIDs. 

PIDs or ('parameter IDs') are codes used to request data from a vehicle's ECU or on board computer. The PIDs for transmission temperature vary per vehicle make and model, and in some instances the PIDs you may find may or may not work with your vehicle (and as such we cannot guarantee that the provided PIDs below will work on your vehicle). 

Please see this guide here on how to add PID's to either Torque or Car Scanner ELM OBD2: https://obd2australia.com.au/obd2-pids/

You can also find a list of PIDs on that guide as well. If your vehicle is not listed or if a certain PID does not work, you will have to do an online search and do a bit of trial and error in order to get this data.