Yes, payment is guaranteed as exchange acts as counter party in any transaction.
As that option is illiquid till yesterday it might have closed at theoretical price or at last transaction price which might have happened few days or weeks ago. If someone is new to markets it is recommended to transact in liquid contracts only.
Follow few basic rules like selecting current month contract only during first couple of weeks of the month, select within 5 to 6 above and below strikes only, check if any activity(volume) is happening or not, said that all mentioned points are just basic but decent to start with and as time goes markets will teach you everything.
Thanks Siva. I have been trading option for last 4 weeks using strategy you mentioned, but mostly intraday. Few overnight positions cost me loss of 15k. But it’s been interesting journey so far with options. Just wanted to experiment with next month contract.