secure connection to localhost

Trying to open a help file linked from a Safari page, I get an error message

Safari Can't Open the Page

"https://localhost:3052/local/assets/helpManual/en/dashboard.html#status" because Safari can't establish a secure connection to the server "localhost".

The web page is the PowerPanel Business 4.4.0 page which provides access to CyberPower's local PowerPanel Business 4.4.0 application, which should connect via USB to my CyberPower UPS unit.

This is a new system which I am trying to set up. The control app running on my Mac also has not been able to establish a connection to the UPS unit.

How can I get Safari to open the help file?