Hi SB. I'm Greg, an installation specialist and 9 year Windows MVP here to help you.
Have you installed Office? Is it showing in Settings > Apps > Apps & Features?
But you cannot set it as default in Settings > Apps > Default Apps > Set Defaults by App > Microsoft Office > Choose a Default > Your installed Excel app (not the trial one at top they'll try to sell you if you choose it).
If it doesn't appear then do a repair at Settings > Apps > Apps & Features > Microsoft Office > Advanced Options > Modify > Repair.
Then it should already claim the default but if not go back to claim it.
I hope this helps. Feel free to ask back any questions and keep me posted. If you'll wait to rate whether my post helped you, I will keep working with you until it's resolved.
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