Although the software is sold by the same company, you will have to purchase the version for Mac because from what I am seeing, it appears that you can install only the version you've purchased. The license of the software is commercial, meaning that download is possible only after you completed the payment procedure. Check your email or access the member's area to see if it's possible to download the Mac version of the software. If it isn't, then you'll need to acquire the Mac version.
Get in touch with the developers to obtain an official statement: https://www.wordsearchbible.com/contact_us