@mrfabulous1 Thank you! I got it working. There were two hurdles in case it helps someone.
1. requirements.txt
I notice it does not like below, which are in my pip list in Colab environment.
torch=1.5.1+cu101
torchvision=0.6.1+cu101
I replaced them with below, and it works.
torch==1.5.1
torchvision==0.6.1
2. The downloadable link for export file hosted in google drive
It was restricted. It needs to be anyone with the link. What a gotcha.
Now it’s running and I can test my weed detector with photo I took.
Let me celebrate for a second. 
And then there is one more problem. Once in a while, it ran out of memory. My export file is 80MB. Does it use that much memory – used over 512 MB? 
