The error, 'The type initializer for 'ABR.AusKeyManager.Keystore.AbrProperties threw an exception' can occur when you attempt to set up the credentials for the first time if accessing HandiTax through Practice Manager.
To resolve, access HandiTax via the HSoft\Apps folder or it's own shortcut icon:
Go to the installation path Hsoft\Apps in File Explorer (Help, About in your program will advise location).
Open the executable HTXX.exe (where XX demotes the current year).
Repeat the process to set your credential.