Install LibreOffice on Macbook correctly?

I recently got a used Macbook Air 2017 and I'm completely happy with it! Now I have noticed that I have to reinstall LibreOffice every time I shut down the Mac completely. As soon as I switch on the laptop, I can't open the documents and Excel files immediately, but have to open the LibreOffice program (image 1), then click on it (image 2) and then it has to be reloaded or "checked" again (image 3) . Why is that? What am I doing wrong? Only had a Macbook for a year in 2019 and now in 2021 I've got one again and don't know anything about it. I'm actually a Windows user. Thank you in advance!

At the moment you have the installer for LibreOffice in your Applications folder, more precisely the installation image, which is roughly equivalent to an imaginary DVD. More precisely: not the image but an alias to this image, the original is probably still in the Downloads folder.

Do what the green arrow tells you to do: grab the icon and drag it to the folder on the right. This is actually not a folder, but an alias (Windows calls this a shortcut) to your Programs folder.

This copies the LibreOffice program from the installation image to the Programs folder.

You can then delete the installation image. Both alias and original.

Easier than you might think. No sooner said than done and it works.