My guess is that you can not change ownership or access because your Samba-root (mapped to 10000 on the host) has no rights to the folder of the container (mapped to user 1000 on the host I guess?).
The solution would be to modify the access...
On my host I have a ZFS dataset looking like this:
NAME MOUNTPOINT
Data /Data
Data/Nas /Data/Nas
Data/Nas/Documents /Data/Nas/Documents
Data/Nas/Photos...