Hi, may I use the Aria Player for commercial purposes, even if I don't buy any of the Garritan libraries yet? I don't mean selling the software itself, but making commercial music with it. I use Windows 10 x64 and Aria 1.959, engine 1.967 .
The ARIA Player is only available as part of Finale, or with a Garritan library like GPO5. So, buy purchasing Finale, you already have one Garritan library.
Yes, you can make audio content that you may sell. All the Garritan libraries' EULAs say:
You can use these sounds in music productions, public performances, and other reasonable musical purposes within musical compositions. You can use these sounds in your own musical compositions as much as you like without any need to pay Garritan Corporation or obtain further permission.
They also ask that you credit Garritan in any written materials, where possible.