Network file sharing not working between Windows 11 & Windows 10

That I should change my Lap Top Windows 11 to 10, that was much better.

I've already tried the "Everyone" security settings on my setup, with no luck... :-(

Thanks everyone for suggestions but nothing seemed to resolve this plus introduced potentially new challenges to be overcome. Good news is that I finally think I've resolved this. Turns out that Windows 11 must need the Security permissions set to Everyone in addition to the Sharing permissions for the Windows 10 host shared drive. Doesn't seem top have been an issue between Win 10 platforms. However, in my situation, looks like a legacy $MfeDeepRem folder in the root directories left over from past versions of McAfee was preventing the Security permissions from being fully enumerated and thus not able to establish Security permissions for Everyone or actually anyone for that matter. Discovered this gem by way of my external USB drive E that I could successfully add Everyone to it's Security permissions and enable mapping. Trying to add Everyone to the C and F drives kept crashing close to the last folder and file which led me to examine and attempt individual folder permissions which exhibited the same behaviors when I tried on the $MfeDeepRem folder and then looked more closely at it's current permissions. McAfee faqs indicated that the $MfeDeepRem folder was supposed to be removed with updates after September 2021 but guess not. And despite running an admin account on the Win 10 system, couldn't do anything with the rouge folder due to limited permissions. McAfee provided a removal tool that got rid of any traces of McAfee including my current LiveSafe. But still had problems getting rid of the $MfeDeepRem folders. Fortunately, one was empty and was somehow eventually able to be deleted but the other had a ton of log folders and files. With McAfee killed, we were somehow able to get rid of it and I was then able to set Security permissions for Everyone albeit on the C drive there were a bunch of restricted system files and folders but otherwise Everyone was enumerated to everything else. Now my new Win 11 laptop successfully maps to drives on my Win 10 desktop. And I'm able to map the other way and also between Win 10 laptop to both. Geez I despise getting new hardware that comes with a 'new and improved' operating system.

Firefox allows syncing of passwords and favourites over any number of machines, including Android phones, but not apps, but then I have been trying for the past few days to download and reinstall WhatsApp on a machine on which I have had to reinstal W10, and the Store won't let me have it "because I own it."

Well, it does allow my passwords, favourites and apps to sync over six machines and an Android phone. I find that quite useful. I can also add new machines which will be activated and licensed using the MS account. It's the Windows Hello that screws it up, so I don't use it.