Can't open D2's app downloader on a macOS Mojave

Hi, I just bought D2 and LOD 30 minutes ago. I downloaded the “downloader app” for both titles but i can’t open them.
I’m not using Catalina, i’m on a Mojave 10.14.6 please help! Otherwise, I will obviously ask for a refund.

Such a waste of time already, I asked for vacations at work, 2 weeks only for playing classic diablo, i was completely hyped now i’m into this cr*p sorry blizz but it’s true. pls help!