MacOS and desktop vs online TurboTax

I used desktop TurboTax Home Business 2020 on a MacOS Mojave 10.14.6 and was told I must upgrade to be able to use TurboTax for 2021. If I start using the online version of TurboTax will I still need to upgrade for 2021 or will the online version for 2021 work on my current MacOS?