It is a limitation of using winbox in WINE. Although it works, it is not designed for it. It works quite well, as I am full time ubuntu, my solution to this problem is:
if you use SCP, you will find that “/” is the root of the file manager, so if you have a file ‘log.txt’ you want to download from the router:
scp @:/log.txt .
this requires SSH access being set up on the router also.
You need to look it by your self the way you installed winbox make it different
I used snap to install it what you need to do is to right click on a file in the winbox file list and click on download then you will be prompt for a location you have to create a folder with a name you can recall and that you are sure is unic in you computer then save the folder and open a terminal in su mode ( by doing sudo -I) then launch the command #sudo find / -name “”
It l’ll search for the folder and voila
mine was as following since i used snap to install it
/home/chris/snap/winbox/common/.wine/drive_c/users/Public/Documents/