Thanks RandyC.
For other users, here the step by step process:
1) In plan view - select all zones.
2) With zones selected, open > Options > Property Manger
In Property Manager
3) Click "New" and give it a "Property Name"
4) Add to Group: should be ZONES
5) Click "Ok"
The new property should remain highlighted.
6) Change Data Type to "Number"
7) Change Default Value to "Expression"
8 ) An "Expression Editor should open.
In the Expression Editor
9) Click Parameters & Properties.
10) Select "ZONES" & "Measured Area" and click "Add"
11) Click the "fx" button and select "Operators" and "Divide". Click "Add"
12) Click the ruler button, select "m²". Click add.
13) Continue with these until it marches the screenshot earlier in the topic.
14) Add the brackets and numbers to match the same screenshot.
Under "Availability of Classifications"
15) Select "Custom", then "Edit" then "Space"
15.1) Under the "Space" tree you can select "Internal Space" and "External Space" and all the sub categories.
I select ALL the sub categories, ie. Access Space, Commercial Space, ect otherwise they don't seem to show in the newly created property
Click "OK" which closes the Property Manager.
Open the Area Schedule's "Scheme Settings" and add the newly created property to your FIELDS / ZONE LIST
NOTE:
Zones MUST be selected in plan when the new property is created.
ArchiCAD24 - since Nov 2020
Revit - 2005 to 2020
Windows 10 Pro
2 screens: nvidia quadro RTX 4000