Excel 2010 and Excel micosoft 365

I have been successfully using Excel spreadsheet from contact until I signed up for Microsoft 365.

I could not access files anymore, saying I needed passcode.  Then I could get sheets with 365 but now not even that.  Asks me to enable macros.  I try.  No Success.

Very frustrated.

Tried reinstalling Excel 10 same problems.

Now I am completely locked out of all spreadsheets.

Please, please help.