Burn Micronucleus bootloader to use ATtiny85 via USB (AVRDUDE)
Looks OK to me.

As I read here (https://github.com/micronucleus/micronucleus) 

1) after having burned the bootloader you will have to use the upload tool that comes with the micronucleus bootloader to flash your programs (not avrdude)

and 

2) you will have to install drivers depending on your OS.

I guess 2) is your problem right now.