why can't enter my license code on turbo tax that I share with my daughter?

Please explain what you mean by "on turbo tax that I share with my daughter"----   The license code cannot be used for online TurboTax.  The license code is only for the desktop download software that you download to the hard drive of your own computer and then use on your computer.   You can use the download to e-file up to five federal returns and the state returns that go with them, so multiple family members' returns can be prepared using the download.

Did you purchase the download and then use online by mistake?

We see people get confused and they keep logging in to online software which will require them to pay at the end.   You need to use the desktop software.   One way to tell if you are using the right software---your tool bar.   Online software has the toolbar in a black vertical column on the left side of the screen.   Desktop software has the tools up on the top of your TT screen.

You appear to be posting from online software instead of the desktop CD/download software that the license code is for.  If you are using online, you are using the wrong program.  You need to switch to the desktop software to get what you paid for.  You have to download it, update it and open it up from your own hard drive to use it.  

https://ttlc.intuit.com/community/choosing-a-product/help/how-do-i-switch-from-turbotax-online-to-the-turbotax-software/00/26129

Did you or her download and install the Desktop program?  Do you each have a License  Code?  

There is a way to have 2 licenses. You don't need to install the second version just enter the License Code. Under Help - Switch Product - Activate new product. Don't know what that will do or what benefit you will get. Don't think it will allow you to efile more than 5.

Or are you trying to enter it into the Online version?  The License Code is for the Desktop program.  You can't apply it to Online.  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