DOXBOX-X won't mount directories I created

Hi! My issue is with DOSBOX-X in a Debian 10 Linux, Mac Mini 2007 32 Bit.
I did one successful test with dosbox and now I’m heaving this error, I don’t know what changed. I have to mount c to run my games, of course. I have created a folder in the root named doswin to put my stuff. I call dosbox by “snap run dosbox-x”. Then I try to mount c by…
mount c /doswin
The result is “Directory /doswin doesn’t exist”! I try to add all permissions to all trough chmod, same result.
I can mount other folders system has created, and than this got interesting. I mount c as /usr for instance - ok c is mounted. Than I create a directory inside /usr. This new directory won’t show up when I list the directory by DOS “dir” command… this is bizzarre!
I wasn’t sure about who to ask for an answer, but it seems to me the way Snap relates with Linux, however you can tell me where is the best place for this issue - Linux forums, Debian, DOSBOX-X (didn’t find a forum), original DOSBOX or whatever.
Thanks for advance, need to finish DOOM II asap!