HI Sanya Good question. This sentence isn't really a very good example of 'proper' English (although it's quite natural sounding), so it's not the sort of English people normally learn. 'To get started' is a synonym of 'to begin' or 'to start' - there isn't really any need for the 'get' in the sentence, but people use to make things sounds more immediate or dramatic. Strangely, the 'got' in this example is not passive voice, it's just past tense. But as I say it's not really very good English. And this isn't helped by the fact they 'getting' in the same phrase, it would be less confusing if they said "we started collecting"

The sentence would make perfect sense and mean basically the same thing without the 'got'. The appropriate form of the verb 'to get' is often added, particularly in speech, when it is not, strictly speaking, necessary. However 'get started' does seem to have a slight nuance that it required some effort to start than 'start' alone. Got is a simple past. As I said, this is a common construction in real life English, that might not be taught in grammar books

Thank you very much. :)

in that sentence, "got started" means "began"