I purchased the Deluxe Turbo Tax today from Costco. I have finished my taxes and now it will NOT let me file them. It says I need to upgrade to Deluxe. I already Did ?

You completed your tax return using the TurboTax online editions and not the software you purchased and should have installed on your personal computer.  Close the browser window for the online edition.

See this TurboTax support FAQ for installing the CD/Download software with the license code - https://ttlc.intuit.com/turbotax-support/en-us/help-article/license-information/install-turbotax-cd-download-software-license-code/L1wFOSXur_US_en_US?uid=ls6ycigh

I see people all the time that have bought the CD/Download Desktop Software but then somehow ending up using the Online version and didn't know it. If that happened to you, you can move your Online file to the Desktop program and continue without paying for Online or needing to reenter your info.

You need to install the program on your computer and move your online return to the Desktop program. How to install the CD/Download program with a License Code
https://ttlc.intuit.com/community/tax-topics/help/activating-turbotax-cd-download-software/00/852971

Then you can download the .tax2023 data file without paying for Online and continue in the desktop version.

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

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

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. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW). Enter some basic information, then go to the state tab and download the state program. Then try to open your existing return, go to FILE - OPEN