I should have tried to figure this out for long. It took a while but here is a nice solution. Basically just use onenote. And to record, I can use audacity and record from pulse. And can use pulse audio control (pavucontrol) to select only system sound.
Simply put. It doesn’t work. But vnc can be set up with the description here. And it is the same as x11vnc (controlling the desktop rather than another vnc).
Spent several hours before realized that Barrier doesn’t not work on 18.04 as host. Should have checked “show log” earlier and that would allow me to figure out earlier. Online it said 18.04 will work for barrier-maxiberta. But snap install can’t find barrier-maxiberta. If I snap install barrier, it results in an authentication error.
Try to look for a free alternative for teamviewer. ssh -X will work but like to control the current desktop directly. It turns out can be done easily with x11vnc. In the host (after connecting say with ssh), start x11vnc with x11vnc -display :0 For the client, simply run vncviewer.
ssh -X doesn’t work out of the box for my 20.04 host. It was solved after adding X11Forwarding yes and X11UseLocalhost no to /etc/ssh/sshd_config at the host. btw, one great way to debug the problem is to turn on the verbose flag. i.e., ssh -vX hostname