However, in Win-XP Pro quick assist, it works the exact opposite as far as I understand - that the host computer (i.e. The reason for my doubt about this is that for the Win-10 Pro computer requesting assistance, it needs a 6-digit access passcode be connected into by the remote computer (in this case a Win-XP Pro computer).

While I found that Windows remote desktop access from a Win-XP Pro computer to a Win-10 Pro computer works perfectly fine at least on a LAN that I tested multiple times on, I'm not sure how Windows Quick Assist would work (or if it even works at all) when a remote Win-XP Pro computer connects to a Win-10 Pro computer to provide it assistance. hosting a remote computer) by a Win-XP Pro SP-3 computer. I'm also wondering whether Quick Assist will work when a Win-10 computer is being assisted (i.e. I'll try it out and see if it works fine between two Win-10 computers. But you will need to login before any assistance is available.Thanks for confirming what I suspected. Any MS mail account will do so Hotmail and Outlook are supported AFAIK.

Ms quick assist