we use SCCM as software deployment and it also installs as SYSTEM account
I would suggest you use powershell app deployment toolkit (PSADT) because if user is still running pgadmin during
installingan later version or uninstalling it can break Pgadmin
https://psappdeploytoolkit.com/
this is what you need as batch script:
vcredist_x64.exe /install /quiet /norestart /noreboot /log c:\windows\logs\vcredist_2013_x64_install_12.0.30501.log
pgadmin4-6.8-x64.exe /verysilent /norestart /allusers /LOG=C:\Windows\logs\pgadmin4v6.8_install.log'
If you want I can share the psadt script as well.
Sascha