How to keep track of time in serverless function in C# (cloud code)

I am writing a battle simulation for my asynchronous auto battler multiplayer and I will use cloud code to run a simulation (only calculations without graphics) in order to authorize the outcome of the Battle. My model is server authoritative. I need a way to keep time for cool downs of abilities and movement. I chose cloud code so I don’t need to host an unity instance in a dedicated server (expensive). I had some suggestions about the client sending info about time but I since I don’t trust the client this is not applicable. I need a way to keep time the way time delta in unity does it under the hood so I can have the same “time-accuracy”. Maybe some library? I don’t know how unity get its time from.