I found the AppData folder via the File>Preferences menu selection in the IDE. The error msg appears to be right -- on my PC I can trace the path down to">4.8.1-arduino5", but there is nothing titled "bin" under that.
C:\Users\asus\AppData\Local\Arduino15\packages\arduino\tools\avr-gcc\4.8.1-arduino5>dir
Volume in drive C is OS
Volume Serial Number is 1A5C-D4DF
Directory of C:\Users\asus\AppData\Local\Arduino15\packages\arduino\tools\avr-gcc\4.8.1-arduino5
05/10/2021 02:27 PM .
05/10/2021 02:27 PM ..
05/10/2021 02:27 PM avr
0 File(s) 0 bytes
3 Dir(s) 227,926,016 bytes free
So, what process sets up these files? Do I have to repeat some operation? I used the package from Digistump. I see there is another package from David A.Mellis. Should I try using that one?
edit:
I tried the package from Mellis. Didn't get the previous error message but the upload failed without indication as to why.
Very frustrating when the instructions are written as if success is a sure thing and there is no assistance when things fail.