TurboTax can help you download the CD/download product on your computer without using the CD. If you use the online product to do multiple tax returns, you have to pay for each return you do. If you already used it to do you own return, you had to pay for the online return in addition to the CD/download product you bought and couldn't get installed. You might see if TurboTax would give you a refund for your online return.
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-contact-turbotax/00/26991
With online TurboTax you only get one return per fee. With the CD/download you can prepare and e-file multiple returns, and e-file up to five of them. You cannot pay for online TT using the license code for the CD/download. If you use online for multiple returns you may have a large amount to pay.
If you are having issues with downloading the software----did you try contacting support for help?
To call TurboTax customer support
https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number
Customer support is available from 5 a.m. to 9 p.m. Pacific time