https://dev.to/oswllt/proxmox-bind-smb-mount-to-unprivileged-lxc-container-the-easy-way-3l4k

add passwords to smbcredentials

nano ~/.smbcredentials
username=plex-user
password=whatever

secure file

chmod 700 ~/.smbcredentials  

edit fstab

//192.168.2.3/Films_4K  /mnt/films_4k   cifs    credentials=/root/.smbcredentials,uid=100000,gid=100000 0 0
//192.168.2.3/films     /mnt/films      cifs    credentials=/root/.smbcredentials,uid=100000,gid=100000 0 0
//192.168.2.3/media     /mnt/media      cifs    credentials=/root/.smbcredentials,uid=100000,gid=100000 0 0
//192.168.2.3/tv_series     /mnt/tv_series      cifs credentials=/root/.smbcredentials,uid=100000,gid=100000 0 0

map shares into hosts:

root@proxmox:/mnt# pct set 102 -mp0 /mnt/tv_series/,mp=/mnt/tv_series
root@proxmox:/mnt# pct set 102 -mp1 /mnt/films/,mp=/mnt/films
root@proxmox:/mnt# pct set 102 -mp2 /mnt/films_4k/,mp=/mnt/films_4k
root@proxmox:/mnt# pct set 102 -mp3 /mnt/media/,mp=/mnt/media