@bobd1830 

If you bought the download from Costco then they should provide you the insructions on how to access that download.   If you bought the CD and want to download the program instead of using the disc then follow the instructions in the CD packaging. 

If you downloaded TurboTax directly from an authorized retailer, your license code should be included in your order confirmation. Check your email or your order history. If it’s not there, you’ll need to contact the retailer directly.

If you obtained the TurboTax CD from an authorized retailer, your license code is printed on the front of the insert in your box. 

These might help

If you Downloaded from a retailer and can't find the License Code

https://ttlc.intuit.com/community/tax-topics/help/i-can-t-find-my-license-code/01/855903

If you have the Turbo Tax CD and can't find the License Code

https://ttlc.intuit.com/community/tax-topics/help/i-can-t-find-my-license-code/01/855902