Downloading the CSV necessarily means authentication, because GuidedTrack has to ensure that it's sending the data to someone who is authorized to read it. Not requiring authentication would effectively make all of your CSV data public, which wouldn't be responsible.
That said, I think it's possible to do what you want. There are probably many ways, but the one I found was to use
httr, which is a wrapper for
curl and has options for authentication.
The following ought to work to get your data into R, just replace
GT_ACCOUNT_PASSWORD with your account details:
GET("https://www.guidedtrack.com/programs/17783/csv", authenticate("GT_ACCOUNT_EMAIL", "GT_ACCOUNT_PASSWORD"))
The above probably needs more massaging to get a vector or something useful out of the data, but it should solve the immediate problem you're facing.
Another tricky bit is that the CSV is streamed to the client, since it might be a huge file. I hope
httpr handles that correctly, but if it doesn't you might see your data truncated after 500 or so rows.