Flashing ESP8266 ESP-12E/12F
On my version of this "Adatper" adapter the io pins were not connected. I patched io 0 to the esp-01 like header, to be able to put the ESP in bootloader mode. On the picture you see a paperclip jumper connecting io 0 to ground for flashing mode. 

Back then I could leave the jumper connected, because the esp8266 run the sketch after upload. In new versions of esp8266 arduino boards package the esptool hard resets the esp8266 so it returns into flashing mode. This can be changed in platform.txt.

I recommend you to buy an esp8266 dev board with USB (Wemos, NodeMcu and similar)