Serveo is an SSH server just for remote port forwarding. When a user connects to Serveo, they get a public URL that anybody can use to connect to their localhost server.
It is necessary to copy the index.html file from the docker container zm to the host and edit with password protection commands and copy back to the zm container
Now edit the copied file by adding the following html scripts highlighted in red in the figure below for password protection as follows.
Following are the outcome at remote smart phone when accessing Zoneminder Console after the two protections above for the localhost and the Zoneminder .
Zoneminder Console is obtained by adding /zm to the port forwarded serveo url of localhost:8080 ( In our case https://abcd2020.serveousercontent.com/zm ).