I tried with both Chrome and Safari on a Mac. The only difference is the filename of the empty text file that gets downloaded. With Chrome it's `OOTS06_UtterlyDwarfed_DigitalEdition_v1.txt` and with Safari it's `OOTS06_UtterlyDwarfed_DigitalEdition_v1.pdf.txt`.
I have downloaded the other OOTS PDFs from Gumroad just fine in the past using the same computer.
jt