i purchased the download already and have the product key. when i go to install it I don't see where i can put in code to upload it

How to get started with the Desktop program, install and activate it
https://ttlc.intuit.com/turbotax-support/en-us/help-article/product-delivery/download-software-turbotax-com/L7u9oLEkq_US_en_US?uid=luqgvzrd

If you are having trouble going to installturbotax.com, you can go here to start the download
https://turbotax.intuit.com/personal-taxes/cd-download/install-turbotax