What error message? What browser are you using? Try downloading it in Chrome. It doesn't like Microsoft Edge. Did you buy the right download, Windows or Mac? Does your computer meet the requirements? They changed this year.
Window System Requirements
https://ttlc.intuit.com/community/system-requirements/help/minimum-system-requirements-for-turbotax-...
Mac System Requirements
https://ttlc.intuit.com/community/system-requirements/help/minimum-system-requirements-for-turbotax-...
