How to change the Transmission download directory (on the router)?

Question

ASUS

There is an Asus router with firmware from Padawan and Transmission on it. So, when I tell him to download to a network folder, and not to a hard drive connected to the router, he writes an access error.
Of course, I immediately created a user with the same name and password as the router and gave him write permissions to the network folder, but the error remained.
Everything works if I make a network folder in write mode for everyone, but this does not suit me.
What could be the problem, maybe in the transcription what is wrong with the user (changed through settings.json)?
Windows network folder.