QUESTION: What is the size limit for a document upload?
There is not a specific limit to the size of file you can upload. There is however, a timeout limit. The document will have 5 minutes to upload. If it is able to be uploaded in that time and does not exceed the amount of document storage purchased, it will be successful.
As an extreme example: You could only upload 1 document, if that document takes up the entire purchased storage limit and your network can complete this in under 5 minutes.