I can't seem to sign up for Plus - It's Just. Not. Working.

Hi all.  I need to D/L a PDF of my 2017 tax return (which I filed using TurboTax Online last year).  I can view my AGI, but it won't let me download the PDF because I didn't use/have PLUS.  I spent over 2 hours TRYING to purchase PLUS, but there seems to be no way availabale to me that actually works.  I tried "Start 2018 tax return", but it wouldn't open up - probably because it's past the deadline for filing?  I haven't filed anything for 2018 because I had little or no income last year.  How can I purchase the PLUS so I can D/L the PDF of my 2017 tax return?  Nothing is working for me at this time.  Any help would be appreciated.