Dear @bryn ,
earlier I was experiencing the same problem as acristancho when trying to download the Yoon-Sun model with Sim4Life light.
As you suggested, I reinstalled the program to gain access to the "generate code" option, which works fine.
However, when I use the generated code to download the Yoon-Sun cV3.1 (posable), which is about 800 MB in size, the download complete successfully but when I try to open it in Sim4Life, I am missing the required license. I'm guessing this is because Sim4Life light does not come with the posable version of the model.
When I repeat the process to download the Yoon-sun V3.1 model which is about 1.7 GB in size, the download does NOT complete successfully and the .zip file is corrupted and unusable.
This is the same error that I experiences before updating Sim4Life and seems to be related to the download size as acristancho mentioned before.
Any suggestions on how to solve this issue as it seems to appear with multiple users?
On a side note, I have installed sim4life on Windows 7 instead of Windows 10. Could this cause any of the aforementioned license issues?