I thought I was downloading Libre Office to my laptop, but only got Writer and Calc. I can’t seem to find out how to get Impress.
Can you tell us your OS and the version of LO?
Some Linux-distributions may not install all of LibreOffice (several remove Base).
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Then check, if you can open an Impress file via menu: File>New-> Impress or Presentation
If this works, all you miss is desktop Integration, nut Impress os already available.