SDK Manager

officially Virtual machines are not supported for flashing with sdkmanager or;
you might be better off installing Ubuntu as a second boot OS to the computer.
On the other hand, Windows might work for writing disc image for nano onto sdcard. [ , ] Moreover, flashing from VM’s although is not supported, still works often.

I have solved the issue, without installing SDK manager as it required large SD card. I have 64 Gb, but did not work. required 128. I find alternatives to install packages. It took long time, but finally succeed.

Would you care to share your solution? Please.