Hi!
I had the same issue recently, but I figured out how to fix it for me so it might fix it for you too!
I made my microsoft account when I was younger and didn't want to lie about my age so I made a fake parent account like any other kid would do.
Turns out, in microsoft family setting, the accounts that aren't the family organiser have any other Internet browser blocked apart from windows edge so the family organiser can easily filter Web searches etc.
For me, the fix was as easy as loging into the family organiser account and unblocking access to all the browsers and now I can download chrome, opera etc on my Microsoft account.
Hope this helps!