Helvetica Font

Hello

I need to add Helvetica Font text to book covers for a client using Photoshop CC 2021 Windows 10 Pro.

The font isn't on Windows. 

Is there a site where I can purchase this font? 

The client is a Mac user, I am a Windows user. 

Let me know if I can get Helvetica working/installed for use on Photoshop.

Thanks!!