Seems my user, pass and URL given me by Express IPTV isnt working. Using Stalker Apple TV App - which is suggesting there may be a alternate URL for "mobile"/Apple TV purpose - waiting on Express support, but if anyone knows the tweak please comment or DM me, cheers!
They only have the one portal.
What portal did they give you?
It's a known issue that not all stalker app versions are compatible with express. Likely this is your issue. That will require you to install an older version onto your device.
Good luck with the Appletv, you'll need it :D