You can purchase and download the 2018 TurboTax software for PC or Mac by clicking on that link.

If you paid for the CD or Windows download you can call in and ask for the Mac download.  You don't need to buy it again. You can install Turbo Tax on 5 computers you own.

Contact Customer Service
5am-9pm Pacific Time
7 days a week
https://support.turbotax.intuit.com/contact/

What is the Turbo Tax phone number
https://ttlc.intuit.com/community/using-turbotax/help/what-is-the-turbotax-phone-number/00/25632

this is a better link to 2018

https://turbotax.intuit.com/personal-taxes/past-years-products/2018