programming external Arduino computers with LP Sigma running Ubuntu

Hello,

I received a new LP Sigma with 500GB disk, WIFI, etc. I added 2TB of additional SSD storage. I decided to wipe Windows and just installed Ubuntu 22.04.  WoW! I am really impressed with how well this computer runs. I have installed the latest Arduino IDE and a few other programs that I use and they all work perfectly. 

My problem is that when a compile a sketch for an externally connected Arduino, say a Nano, and I try to download the binary to the external Arduino, I get the "avrdude stk500_recv(); programmer is not responding" error message.  I select the computer board and Arduino as ISP in the tools menu with "ACM0" as the port.  THis is what I use on my regular Ubuntu computer and it has worked fine for 100's of programs on, at least, half a dozen different Arduino computers including AT tiny 85's, Nano, Uno, Mega, and ESP32's.  Does this work on a Sigma? and, if so, can you give me an idea of what I am doing wrong?

Thank you in advance.

Bruce