As per the CRA for tax years 2017 to 2023- error code 15 means: 

You have indicated this is a pre-bankruptcy return. Please delete the selected financial data statements. They should not be transmitted with a pre-bankruptcy return.

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Most first-time filers can't use NETFILE, they need to print and mail their returns.  Select the "File" section from the left menu if you use TurboTax Online. Then click "Print & Mail your return(s)" This will print a condensed version of your income tax return to mail out.

This CRA webpage has a list of where you can mail your return.

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