I have direct x 12 and feature levels 12_1. But the fuild brush is grayed out.

What is your GPU? It should show up in Chip Type and DAC Type but it's missing...

Check the 'Notes' section at the bottom, Microsoft Basic Display Adapter is a generic Windows driver, normally it'd show something Intel / AMD / Nvidia. Find your gpu model and update your drivers from the manufacturer's website.

close animate

restart your computer 

open animate

check the fluid brush