I am trying to download the software to allow me to join a meeting that will be held via Zoom. Found advice here https://linuxhint.com/install_zoom_ubuntu/ So I went to the Zoom web page chose the appropriate package but when I hit the download button I got the error message "could not be saved because the disc/folder/file is write-protected" even before I had been asked the directory in which I wished to save the file.

Is my whole disk write-protected? How do I install software if this is the case?

That is extremely unlikely! It's more likely that you launched the browser from somewhere in your system where you don't have write access.

You need to be logged on as yourself (no sudo!) and in your home directory when you launch your browser. The file should then go into your Downloads subdirectory, where you certainly should have write access.

It might be an idea to open your browser's Preferences dialog and check that the preferred location for downloads is correct. My FF Preferences says "Downloads" which would be interpreted as the Downloads directory within the directory from which FF was launched. If you launched it from somewhere other than the home directory, FF will get very confused.

1 members found this post helpful.

Hazel
Many thanks for your assistance. Apologies for the delay in responding but domestic duties took priority.
Originally I had simply launched Firefox by clicking on the icon on the taskbar and hence had no idea in which directory the laptop considered me to be launching Firefox. So I closed it all down and restarted [which led me to have to solve another problem but I'm not going to cross post]. Once that was resolved I opened the terminal and launched Firefox via a command line. It then worked and allowed me to install zoom. I presume that effectively I was following your instruction.

As for your last paragraph [which I didn't see earlier] the download dialogue gave me the option of opening the file using gdebi so I have not yet saved anything.

Every running process has a "current working directory". That's part of its environment. It's usually inherited from the parent process which, in the case of a graphical browser, would be the window manager. And that normally gets launched from a script in your home directory. But if you have been exploring your system before you start up the desktop, things could get mixed up.

Restarting the desktop is always a good first step when you get this sort of annoyance.

As you are a newbie and you are following a set of instructions, my advice would be to follow them strictly until you know enough to vary them. I have looked at your link and they do in fact use gdebi to open and install the package after downloading. I'm no expert on gdebi (I've never used it) but I think that using it instead of downloading would only give you information about the contents of the package. I would say download it first, then unpack it.