I was wondering wether it is legal or not to download software from these sites.
No, it's copyright fraud and illegal in most countries.
Also,
1. Quite often you are purchasing a licence to use the software. If you use the software you download you are using it without proper licence, which is illegal.
2. The site you are downloading from is doing it illegally. They do not have the right to copy, distribute or resell the product. That doesn't put you the downloader in a good legal position either if you knowingly download from them.
3. They're an illegal site asking for credit card details where no credit card company would allow payments to be taken. Expect fraud.