You will find the arcviz.log file for Arcadia Instant under the following subdirectory on Windows OS:
C:\Users\<username>\AppData\Local\Arcadia Data\Arcadia Instant\arcviz.log
You will find the arcviz.log file for Arcadia Instant under the following subdirectory on Windows OS:
C:\Users\<username>\AppData\Local\Arcadia Data\Arcadia Instant\arcviz.log