How to read MS SQL backup file on Mac
If you have or install Docker on your Mac, you can install Microsoft SQL Server in Docker from:

https://hub.docker.com/_/microsoft-mssql-server

When you have the server running locally, you can install the free Azure Data Studio for macOS from here:

https://docs.microsoft.com/en-us/sql/azure-data-studio/download-azure-data-studio?view=sql-server-ver15

That is a graphical tool that will let you for example restore the backup file you have received. You can then export the data in the format you need to continue working with it with other tools.