How to download games onto secondary hard drive (SSD)?

I installed a spare secondary SSD hard drive (500 gigabytes) into my laptop (Acer Predator Helios 300) in order to download Call of Duty: Modern Warfare.

However each time I try to download it, my computer still tries to use the primary hard drive and I don’t see an option to save it to the second one. Also, my computer seems to recognize the SSD but I can’t use it as a download directory from the Battlenet app.

Thank you!