When users attempt to log on to SquaredUp they receive a browser-based login prompt.
The following error is logged in the SquaredUp log file
If users are being presented with the SquaredUp logon screen see Users are unexpectedly presented with the SquaredUp logon screen
SquaredUp accesses SCOM using the end user's credentials. When Windows authentication is being used and SquaredUp is deployed on a dedicated server (not a SCOM server), the end user first authenticates with the SquaredUp web server, and then the SquaredUp web server impersonates the end user and authenticates with the SCOM Management Server. This requirement to authenticate a second time is known as a 'double-hop' and requires Kerberos delegation to be configured correctly.
Kerberos delegation involves complex configuration. It requires Kerberos authentication to be correctly functioning between client, web server and management server, and for configuration such as Service Principal Names (SPNs) to be configured correctly.
Please follow the guide here How to configure Windows authentication.
And run through the Troubleshooting Kerberos article.