The links on your page are going to a WordPress 404 Page not Found page.
It looks like you’ve installed Backlight in the folder: alexjeffriesphotographygroup.com/lightroomapp/
It also appears that you did a full install, that is, an installation that assumes Backlight will be the basis of the site. That is why I’m seeing a Backlight page here:
I’m really not sure how this setup works inside of a WordPress installation, and it may be the cause of the problem you’re seeing.
Usually, people using WordPress for the site but Backlight for their galleries will install the backlight/ and galleries/ folder in the root of the site (but only the backlight/ and galleries/ folders, not the index.php or .htaccess files), rather than a sub-folder of the site. But I don’t see why it wouldn’t work in a sub-folder.
Here’s my guess:
So one problem may be that the index.php and .htaccess files in the root of the unzipped Backlight-installer folder have been uploaded to your lightroomapp/ folder. Try removing them.
Also check that the Site URL in Backlight Settings reflects your Backlight installation. Since Backlight is not installed in the root of the site, try using
https://alexjeffriesphotographygroup.com/lightroomapp/ as the Site URL.