I already paid for turbotax deluxe from best buy. why do I have to pay again?

Did you install the Best Buy program and Activate it with the 16 digit License Code?  Somehow you got into the Online version.  

If you have a License Code you need to install the Desktop CD/Download program and not use the Online version.  How to install with a License Code

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

Sorry you can't apply the Desktop CD/Download program purchase to the Online version.  They are separate prices and work different.  You have to pay for online and try to get a refund for the Desktop program.  Or switch to your program.

If you already started in the Online version you can move your return to the Desktop program even without paying for Online. 

First download the .tax file from the Online version,  

https://ttlc.intuit.com/community/saving/help/how-do-i-save-my-turbotax-online-return-as-a-tax-data-file/00/25740

Then see, How to Switch to Desktop,

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

After you get the program installed the first thing to do before you open your tax return is to update the program and install any state programs you had.  So you first might need to start a fake return to be able to download the state program (go to FILE - New)

Then you just OPEN the .tax2023 file, go up to File-Open.  You don't import or transfer it.