Need help installing D-Link DAP-1620 B1

Yes, it was.

Perhaps try this workaround: D-LINK recovery mode (DIR-882 DIR-878 DIR-867) - #4 by dirkomatic

EDIT: just tried 24.10.0-rc2 with Edge. At first there was no blinkng, but around 80% it started blinking and the device rebooted ~30 seconds after finishing. Installation works fine.