If it is inside a php block, you will only need to set the value as
not with the PHP echo command...
But you will want to concatenate it with the other stuff in the variable so it is clear to PHP how to process...
for example, if you folder path is "/images/", when you set the variable, your code should look like this
'UploadFolder' => "Members/PrimarySchools/".$row_OrgInfo['OrgID']."",
Remember to set the permissions correctly in the parent folder, as well. You have to enable write permissions of the Primary Schools folder in order to create folders within.