Thank you for your answer.
I tried everything MightyOhm.com advised, ie adding the file to etc/udev/rules.d, I tried GROUP admin, I tried GROUP myusername, I tried several priority levels, nothing worked for me
AVRDUDE 64 bit patch is included since version 5.5-2, my version is 5.11.1.
I am sorry if it looks like I did not try to find the answer myself.
I don't want to bother people, so I tried a lot first, I failed, so I had to ask.
I am not experienced user
Thank you, Chompey.