What parameters is the system asking for? What satellite or TV service are you wanting to get? If you're wanting Freesat then the satellite dish size is important - how large is yours?
EDIT
Just noticed that your thread title asks about $ly. If you mean $ly UK then dish size is important for the FTA channels (BBC, ITV C4, C5, etc) although less so for $ly's encrypted offerings. What does become important for $ly is which receiver you are using as it has to be one of their own and I have a feeling that there's a dedicated receiver incorporated into the satelite system.