Can any body help? I am using older version of mac os (OS 10 or so) and just purchased the software which not compatible. What is the solution?

[DoninGA]

Return the software that you purchased for a refund.

TurboTax for Mac only supports - 

macOS Monterey 12 or later (macOS Big Sur 11 not supported)

• Specific macOS: macOS Monterey 12, macOS Ventura 13, macOS Sonoma 14

If you wish you can use the TurboTax online editions - https://turbotax.intuit.com/personal-taxes/online/file-your-own-taxes/