Check your Windows Event Viewer > Windows Logs > Application and filter for “Orchestrator”, and “IdentityService”. Review the Errors found.
Additionally within your Web.config file you can adjust your httpErrors attribute errorMode="Custom" to reveal more details by replacing Custom with DetailedLocalOnly (Default if errorMode attribute was not provided) or Detailed
With DetailedLocalOnly revealing the errors details if browser from the local host only.
More details about httpErrors can be found in the following article for IIS.
If you can provide more details about the error, we’d be happy to offer some suggestions.