If you purchased the 2018 desktop edition you should be able to download the installation file from your download account using the same User ID you used to purchase the software - https://shopping.turbotax.intuit.com/unified/downloads?route=myaccounts
If you have not yet purchased the 2018 desktop editions then go to this website to purchase, download and install on a personal computer one of the 2018 desktop editions - https://turbotax.intuit.com/personal-taxes/past-years-products/
See this TurboTax support FAQ for downloading the software purchase - https://ttlc.intuit.com/community/installing/help/how-do-i-download-the-software-i-purchased-at-turb...
