Mac won't recognise LibreOffice as an App to open odt files

I have just bought a new MacBook Pro and downloaded the version of LibreOffice for Mac processors. However when I try and select LibreOffice as the default app for opening .odt files, LibreOffice is greyed out in the list of apps, so I can’t select it.

Any suggestions?

This site is about LibreOffice. For questions related to OpenOffice, please ask at https://forum.openoffice.org/.

Sorry, I meant LibreOffice. I’ve now edited the post.

If I open the Applications window there is a black arrow pointing to the bottom left-hand corner of the LibreOffice logo. Which suggests that the Mac doesn’t recognise if as a legitimate App perhaps?