I tried putting it where you pointed me to but faced the same error. I put the avr file in the directory C:\Users\MUY1PLY\AppData\Local\Arduino15\packages as suggested by another user and got further but now I'm getting different errors.
Downloading packages
arduino:avr-gcc@7.3.0-atmel3.6.1-arduino7
Failed to install platform: 'arduino:avr:1.8.6'.
Error: 2 UNKNOWN: Get "http://downloads.arduino.cc/tools/avr-gcc-7.3.0-atmel3.6.1-arduino7-i686-w64-mingw32.zip": dial tcp: lookup downloads.arduino.cc: no such host
Downloading Firmata@2.5.9
Firmata@2.5.9
Installing Firmata@2.5.9
Installed Firmata@2.5.9
Downloading Servo@1.2.1
Servo@1.2.1
Installing Servo@1.2.1
Installed Servo@1.2.1
Downloading TFT@1.0.6
TFT@1.0.6
Failed to install library: 'Arduino_BuiltIn:1.0.0'.
Error: 13 INTERNAL: Can't download library: Get "https://downloads.arduino.cc/libraries/github.com/arduino-libraries/TFT-1.0.6.zip?query=depends": dial tcp: lookup downloads.arduino.cc: no such host