Thanks for new logs. Now, script works correctly, package is successfully downloaded, installation parameters are ready and installation itself of PKG file is started. Unfortunately more details of installation failure will be available in different log file:
/var/log/install.log
but in case of macOS 10.15 it won't be meaningful, as in such case, even executing of helper tools bundled in installer with fail. There are multiple reasons for this:
ERA 6.4 Agent for macOS is 32bit application and support for them was dropped in macOs 10.15
ERA 6.4 Agent is not notarized, which is process required for all applications to be installed on macOS 10.15
ERA 6.4 Agent might try to use old OpenSSL library available in macOS 10.15 resulting in operation abort
Unfortunately that is hard to confirm without testing or more date, but ERA 6.4 was definitely not tested in such environment. Errors seems to be more related to installer script, nor ERA Agent, but it might have the same issue - incompatibility with macOS 10.15 environment.