usenet.nl advertises the availability of resources that it turns out are not available. But you don't know that until you have signed up. So they promise a free 14-day trial, to convince people that it is worth investigating further.
Just one look reveals that there are few if any worthwhile resources to download and virtually nobody would ever willingly pay for membership. So usenet.nl have to make their money by ensuring a substantial fee becomes payable by every person who applies for the 14-day "free trial".
Some people have reported not realising that they were signing up to anything other than a free trial. That is because the advertised offer is designed to mislead. Other people have reported how difficult it is to cancel. Deliberately difficult, one assumes.
And usenet.nl knows that cautious people will choose not to enter their credit card or paypal details. So they scam those cautious people by instructing a debt collection agency to harass for payment of an invoice that has never been issued, in respect of services that were never used, knowing that the threat of imminent legal action (with ever increasing "legal costs") will eventually wear down even the most resilient law-abiding citizen.