Docker: "Permission denied" error with changed download location

How do I manage the permissions so Tribler has access to a folder outside of Docker container?

I’m trying to change the download location within the docker container…

FROM:
-v $HOME/Downloads:/home/tribler/TriblerDownloads

TO:
-v /media/sf_share/Downloads:/home/tribler/TriblerDownloads

I get ERROR:
[Errno 13] Permission denied: ‘/home/tribler/TriblerDownloads/credit_mining’

I notice that Docker will create the TriblerDownloads folder as root, and the user is “tribler”.
Not sure if the created folder owner “root” comes from root user of the docker container, or the host root user.

Thanks.