cant read conf file

[aikastor]

here is what docker logs say agter running commands:
2021-01-02T20:17:31.951275426Z Options error: In [CMD-LINE]:1: Error opening configuration file: /vpn/client.conf

this is my run.sh file:

 docker run -d --name vpn-client \
  --cap-add=NET_ADMIN \
  --device /dev/net/tun \
  -v /home/vpn:/vpn \
  ekristen/openvpn-client --config /vpn/client.conf --askpass /vpn/client.pwd --auth-nocache

here is what the directory looks like:

what might be the problem here? could you please advise?