How can I control the number of images users can upload?

Please make sure that you have installed “Kaya Roles Manager” plugin.

Navigate to “Users > Kaya Roles Manager > Posts/Meta box limit”, where if you can not see any roles already created then create a user role as per your needs. If you would like to create New role then “Add New Role” which at the top of the page, and select “user” which is default role for “KTA-Registration” form.

Check this screenshot.