Anyways thank you for your help!!! 
Hello gents,
I just installed Truenas and coming from OMV. Despite the fix and doing all modifications described by the community… I am unable to get rid of the Reolink message.
Anybody else having this problem?
From Winscp and Filezilla I can login correctly plus write permission.
Since I cannot create a vault with TRUENAS, in reolink I gave the absolute path to the CCTV folder. Is maybe that the problem? Where I can find the ftp logs in Truenas?
thanks of course 
I respond myself.
Turns out that reolink does not accept absolut path and it only accepts folder name.
In the remote directly I was putting /mnt/POOL/FOLDER and it was trying to create a folder name ‘/’.
I put home folder to the user and now all works fine.