With Mojave (10.4) and later, you'll need to manually allow our remote control software (Remotix/Acronis) access to remote control your computer. Here's the official instructions from Remotix/Acronis, but here's the short version on how. (Note, this software was originally called Remotix, but got rebranded to Acronis, so you may see either name.)
- Head to the Apple Menu and select System Preferences
- Select Security & Privacy
- Select Accessibility from the left
- Select Privacy at the top right
- Check the box next to Remotix. (It may be listed as Acronis Cyber Connect, Remotix Agent or Remotix QC)
- Repeat this process for "Screen Recording" as well.
- Close the Security & Privacy System Preference.