Fyi: the AT binary isn't available yet because it isn't production-ready. The current AT firmware is compiled with a non-production version of ESP-IDF; apart from that there's also a bug related to AT+RESTORE that we need to fix. We'll edit the git repo to kill the non-working download link for now; expect a binary somewhere after we release ESP-IDF 2.0.
I need the AT binary firmware to control an ESP-WROOM-32 from an arduine Mega2560 board. Does anyone know if the AT binary still is under construction and when it will be available.