I want to try Torbox, but i need to understand something

I am looking for something better than Realdebrid. And a lot of people are mentioning Torbox. Well, i have to ask some questions. And i will be using it monthly and mostly for downloading. Although i will try streaming in my own network at home.

What does it mean with "Concurrent Slots"?

"Unlimited Downloads" - In which way? Over Direct Downloads (Rapidgator & co)?

"Unlimited Usenet Download" - I have to try that out. I never used it.

"1TB Max Download Size" - Ok, that i understand. But under which criteria? Because Usenet and other Download is "unlimited".

I’m asking because i use the most of the time Rapidgator. And i would like to change from storing the media on a harddrive, to keep it online till i watched it. I hope that somebody understands what i mean.

https://imgur.com/a/I9j99Eu