iPhone update in Apple Devices app: Backup storage error

I’m trying to update my iPhone using the Apple Devices app. It downloaded the firmware but automatically prompts for a backup. I don’t want to back up my data. Is there a way to skip the backup process? If I do continue, it says there’s not enough storage on my PC. However, I have enough storage and my iCloud backup is 25GB. My C drive on the PC has 40GB left.