On your ILLiad Web Server, from a Command (CMD) window that you opened up by right-clicking and "Run as Administrator," use this command:
c:\windows\system32\inetsrv\appcmd.exe set config "Default Web Site/ILLiadWebPlatform" /section:requestfiltering /requestlimits.maxallowedcontentlength:120000000
There is no need to restart IIS or the server, the change is immediate.