Steps to reproduce:
1. Open an empty project on Mac or HDRP template
2. Add HDRP via package manager (if new project)
3. Run HDRP wizard (if new project)
4. Make a standalone mac build
5. Launch application

Expectations:
Application launched without issues
Actual result:
Application opens with a black blinking screen

UPDATE:
Tested again with Unity 2019.3.0a12 and HDRP 7.0.1
The issue is still there(blinking), but now you can see "Trial version" in the middle of the black screen.