Hi @thekarrzgmail-com, it doesn’t look like your photos completed uploading. If you can not get small JPGs to upload here on the forum, feel free to use this link to share them with me.
Yes, it is true that the designer could use a horizontal image when designing a vertical cover. They may not choose to use the photo to cover the entire background. So, yes you may submit horizontal photos. However, I think it would be better to compose shots vertically anyway leaving blank space where text and design elements could go, just in case the designer likes your photo and still wants to use it full page.