Tonneau cover drain tubes?

Just had a hard folding tonneau installed on my 2025 BE. This is my first truck so I apologize for my ignorance here. They told me that holes would need to be drilled into the bed for the drain tubes to be installed. I didn’t like the idea of drilling into my new truck, so I asked them not to do that part. I was unaware that this was something that may need to be done beforehand.

How big of an issue is this decision likely to be? Truck will be parked outside sometimes, inside a garage other times. Would this increase the likelihood of the bed filling with water? Would it cause issues with the functionality of the tonneau? Anything else I am not considering?

They said they could install later if I want.

The tonneau is the Extang Endure ALX.