trying to Install ESP8266 Filesystem Uploader in Arduino IDE but ERROR..........

Arduino: 1.8.9 (Windows 10), Board: "Generic ESP8266 Module, 80 MHz, Flash, Disabled, All SSL ciphers (most compatible), ck, 26 MHz, 40MHz, DOUT (compatible), 512K (no SPIFFS), 2, nonos-sdk 2.2.1 (legacy), v2 Lower Memory, Disabled, None, Only Sketch, 115200"

SPIFFS Not Defined for Generic ESP8266 Module, 80 MHz, Flash, Disabled, All SSL ciphers (most compatible), ck, 26 MHz, 40MHz, DOUT (compatible), 512K (no SPIFFS), 2, nonos-sdk 2.2.1 (legacy), v2 Lower Memory, Disabled, None, Only Sketch, 115200

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Is ESP8266 Filesystem Uploader for uploading files into the SPIFFS on the board? You have selected a board that does not have SPIFFS (512K (no SPIFFS).

I dont know much about ESP8266 on Arduino (I don't know if that memory size can be used with SPIFFS, or whether it can only be used for boards with a larger flash chip), but I know you can't store stuff in SPIFFS if you've selected a board definition that doesn't have SPIFFS