Background: A few months ago, my company had an issue which resulted in creating a new domain, and migrating all computers and servers to the new domain, including a Sharepoint 2010 installation. At that time, we had the option to edit MS Office documents in the browser (specifically Word and Excel). Since that time, only some Excel files are able to be edited in the browser.
I did some research, and it seems that we need to install Web Apps Server on the Sharepoint server. (although it wasn't installed before, and I'm not sure what the difference is in needing it to open Office files now). I downloaded it and installed it without an issue, but when I ran the configuration wizard, I got an exception of type System.Security.Principal.IdentityNotMappedException
error. The entire log file is at https://docs.google.com/document/d/1SeVgAkF7R3cnO3o6h3Ehf9zT1nCUzbt5Jptv6RFj7PA/edit?usp=sharing: