We use Join.Me (a Log Me In company) for customers to share their screens for support and training. MacOS may require that users allow the Join.Me app to share the screen. To ensure a successful screen share, please set your security settings in advance of sessions. This should only need to be done once.
> Apple icon > System Preferences
> Security & Privacy > Accessibility > check the Join.Me app
then
> Apple icon > System Preferences
> Screen Recording > check the Join.Me app
This will allow you to share your screen for support