I bought Turbo Tax at a store and it's a DVD/CD but I don't have a drive on my computer. How do I download what I've already bought?

There should be a card in the CD case on on the CD envelope that says how to download it and you will need the 14 or 16 digit code from it to enter.

How to download Turbo Tax instead of using the CD

https://ttlc.intuit.com/community/installing/help/i-bought-the-cd-but-my-computer-doesn-t-have-a-cd-drive/00/26450

And see this.  How to install with a License Code

https://ttlc.intuit.com/community/tax-topics/help/activating-turbotax-cd-download-software/00/852971

You can download your software from TurboTax website with your license code.  Follow the steps in the TurboTax Help article; I bought the CD, but my computer doesn't have a CD drive.

For additional information, refer to the TurboTax article How do I install and activate my TurboTax Desktop product?

@trimpes