If you are trying to update TurboTax 2018 to the latest version, this FAQ can help: https://turbotax.community.intuit.ca/replies/2868252

If you have the 2017 version of TurboTax, then it can’t be updated to 2018. Each version only has the forms and information needed for only one year. You can purchase a copy of TurboTax 2018 here: https://turbotax.intuit.ca/personal-tax-software/download-tax-software.jsp