With the introduction of Curator 2.3 and beyond, there are new requirements for .NET. Without installing the proper .NET Frameworks, the admin/client web applications may fail.
Error - Could not load file or assembly 'netstandard'
Resolution - The above error occurs due to .NET version 4.7.2 not having been installed on the relevant DD server. Without this, the website is unable to load all of it's resources causing the site to fail. Installing the below version of .NET AND restarting the server should resolve the issue.