What shall I do after I allowed the Fancy World Wide remote operate on the MacBook?

John Galt wrote:

First please review Phony "tech support" / "ransomware" popups and web pages - Apple Community. The right thing to do would have been to close the web page and just forget about it.

Now that you contacted "Jason Ken", a criminal, and (presumably) agreed to let them in and root around your Mac, the possibilities are essentially limitless. He or she would have had unfettered ability to do anything you could do — as an authorized user of that Mac.

Including installing key stroke logger spyware – which might have been misleadingly named something else, so that you wouldn't realize what the criminal was installing on your system.

If that was in place, they could sit back and wait for you to enter account names and passwords, and bank and credit card account numbers.

First please review Phony "tech support" / "ransomware" popups and web pages - Apple Community. The right thing to do would have been to close the web page and just forget about it.

Now that you contacted "Jason Ken", a criminal, and (presumably) agreed to let them in and root around your Mac, the possibilities are essentially limitless. He or she would have had unfettered ability to do anything you could do — as an authorized user of that Mac.

In an abundance of caution you should follow the recommendations in that User Tip, under its Appendix. However, only you can know or suspect what actions that criminal may have taken since you were present and watching whatever was being done. No one here could hazard a guess what that may have been.

In most cases, those criminals are simply seeking the low-hanging fruit: your credit card number, bank account information, that sort of thing. Money.