That record feature is not here in the USA and the Ambassador usually refers you back to your country's support.
But since this is model and location specific I can only add what little I know. So far you want a size HDD and USB 2.0 drives that the maker tells you that should work. On average that's the usual wall powered USB 2.0 500GB drive. Sometimes you find folk griping about USB 3.0 issues or 4TB drives but those are a bit bleeding edge for TVs.
Also, the recorded content so far is locked to the TV that recorded it. Some folk fly apart at the seams when they "discover" that. But I've shared it so you don't have to discover it.
I have recently purchased a Samsung smart TV which comes with embedded Freesat/Freeview, rather than a "set top box".
With this technology how can I record/replay programs? Is it possible to use a port to an external disk type and if so any specifics.
Is it possible to use one of the more advanced recorders using the embedded license an if so how?