Since he says that he's not sure if they work, perhaps he doesn't know how to test them locally? Levels will appear at the bottom of the custom map list if placed in the following location:

C:\Users\[PC NAME]\AppData\Local\deadbolt_game

If some of the maps are intended to be played in a sequence via level transitions, a zip folder containing the relevant .nc files can be uploaded instead. A more in depth explanation of the process can be found in the "Uploading And Updating A Level" section of this guide:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=761140674
Otherwise, I'm afraid he'll probably just need to upload them all one at a time.

thank you so much for the answer
I really appriciate it