First from Microsoft:

Microsoft are continuing their quest to make downloading spreadsheets with macros ever more difficult, and now any downloaded spreadsheet has VBA code disabled by default. Unblocking the code (if you know and trust the source of the file) is quite easy. Find the file in File Explorer, right-click and select Properties, then select “unblock” down the bottom:

If you leave the file blocked however, and try to enable the macros, Microsoft will take you to a page on their website that says:

A potentially dangerous macro has been blocked
Macros can add a lot of functionality to Microsoft 365, but they are often used by people with bad intentions to distribute malware to unsuspecting victims.

Which is fair enough, but then it says:

Macros aren’t required for everyday use like reading or editing a document in Word or using Excel workbooks. In most cases you can do everything you need to do in Microsoft 365 without allowing macros to run.

Which is rather like saying you can do everything you need to do in your car without enabling top gear.

Coincidentally, the same day I had the problem with the download I found a new website dealing with using Excel with VBA for structural engineering design:

Lucas Beattie

where the very first article was:

Full article