Setting up a Mac to allow control via Chrome Remote Desktop for support can be a little tricky, these are the steps that you will need to complete to get it set up.
1. Open https://remotedesktop.google.com and click the download arrow.
2. Click Accept & Install
3. Double click the Chrome Remote Desktop Host.pkg file to start install
4. Click continue
5. Click Install
6. Click Close.
7. If prompted, it is safe to Move to Trash
8. Returning to the original page, click GENERATE CODE. (If there is still a download arrow, refresh the page first)
9. Click Share if prompted.
10. Click Open System Preferences to access the setting to allow Chrome Remote Desktop to actually control the Mac
11. The option allow Google Chrome to control the computer is not available until you click the padlock on the lower right of the dialog.
12. Check the option to allow Google Chrome to control the PC. Lock the padlock and close the dialog.
From this point, you can open https://remotedesktop.google.com , select Remote Support and GENERATE CODE, then give this code to the support person to share your screen with them.