It looks as if your corporate proxy is intercepting the HTTPS request, and then changing the certificate, so as you say you’ll need to inject the company CA certificate in to the container.
Assuming this is Xibo 1.8.7, then it’s based on Alpine Linux, so the guide here will give you the details:
In short, copy the CA certificate file (probably with a .pem extension), to /usr/local/share/ca-certificates inside the container, and then run update-ca-certificates.
To copy the file in to the container, you can use docker cp:
To run the update-ca-certificates command, you use docker exec -ti containername update-ca-certificates, where containername is the name of your cms-web container.