Membership signup/renewal erroneously reports missing fields after upgrade to 4.7.3
This may all be stuff you already know.

If you have a look on the Title and Settings for that page eg

civicrm/admin/contribute/settings?reset=1&amp;action=update&amp;id=1

you should see that you have 'allow individuals to contribute 'on behalf of' an organisation' ticked. And below that it should specify the Organisation profile in use. You can either Edit it via that page, or go direct to Profiles.

NOTE: at civicrm/admin/uf/group?reset=1 it may be on the Reserved Profiles tab, which might be why you aren't seeing it.

on the page at https://oaem.ca/civicrm/?page=CiviCRM&amp;q=civicrm/contribute/transact&amp;reset=1&amp;id=1 I do not see the 'on behalf of' checkbox which I do see on your old screenshot - is that because you have now made it required?