Ultimate Auction Pro plugin uses directly ‘administrator’ role to protect all its menu items. Moreover it intensively checks if user has the ‘administrator’ role through its code.
This means that is no chance to replace ‘administrator’ to some other role without headache after every plugin update.

Contact plugin developer. It’s quite better to use user capabilities (or custom role) to protect the plugin, in order a client may decide himself to whom allow to use this plugin.