That dialog is for the "Custom" tools which use a python script, and not for the confusingly named "python" toolbox, where you specify everything.
So assuming you are trying to create a "custom" python tool, then...
Fill in the General options first.
Next provide a Name for the tool parameter (which you generally, assign in your script using GetParameterAsText, or sys.argv)
Provide the type etc and move on to the next parameter.
Perhaps you didn't specify parameters for the script (?)
Comparing custom and Python toolboxes—ArcGIS Pro | Documentation
I use Custom toolboxes since I screengrab the dialogs for documentation and you can still edit validation code for the tool
... sort of retired...