Downloading GarageBand for MacOS Sierra Ver. 10.12.6

My question is I don't have Garageband on my iMac 27 inch from late 2010, and I did the updates and right now I seem I cannot download and install the Garageband program onto the computer from the app store. Is there another way that I can download an earlier version of GarageBand that would be compatible with the Mac?

I want to use the mac for connecting an electric piano to the usb port, but I would like to have the software to use it. Can someone help me, thanks.