The TurboTax desktop editions and the TurboTax online editions are totally separate programs.
You can transfer the 2018 tax data file from your computer to the 2019 online tax return.
See this TurboTax support FAQ for transferring when using the online editions - https://ttlc.intuit.com/community/entering-importing/help/how-do-i-transfer-last-year-s-return-into-...
