I recently purchased Photoshop Elements and Premiere Elements 2020. I agreed to let the Elements Organizer catalog my media. It took over one day and my computer was unusably slow during that time. But it was still unusably slow when it finished and I discovered that what had been 120GB free on my hard drive was now down to just a few hundred MB. I uninstalled both applications and deleted any related folders then installed Photoshop Elements again, this time intending to NOT use the Organizer. But just now when I clicked "Create" then "Slideshow" it tried to open the Organizer and failed as there was no catalog and it asked me to find the catalog or make a new one. I have over 150,000 jpegs alone, not to mention videos and other media the Organizer wants to catalog. Is it possible to use this application without the Organizer? If not then I can't use it or I would have to upgrade my hard drive, which is 1TB already. I have a Dell Inspiron desktop running Windows 10 v1903.
I have no idea why importing files into the Organizer filled up your hard drive. This should not have happened. I can only guess that because of the size of your media files, a number of temporary files/folders were created and didn't get deleted. I have over 170,000 photo and video files in my catalog. The catalog folder occupies 18.5 GB of storage space on my system drive. (All of my media files are on other hard drives.)
Yes, the Slideshow creator does require use of the Organizer. If you don't want to try creating a full catalog again, I have a couple of workarounds for you.
Create a new catalog and add only the media that you want to include in the slideshow. (There is a maximum of 250 media files allowed.)
Click on the Slideshow button in the toolbin of the Organizer.
Create a new catalog and add just a single file to it.
Click on the Slideshow button and a new slideshow will be created with the single file.
Click on the Media icon;
Click on the Add Files button
Use the Add Phots from Folders dialog.
Delete the original file from the slideshow.
If you want to have another try at creating a full catalog, here are some points to consider:
Yes, it takes a long time to import 150,000 photos and videos.
After the files are imported, media analysis kicks in which totally degrades your computer's performance while it is being performed. However, you can turn it off (selectively) in the Edit>Preferences>Media Analysis dialog. Auto Creations seems to be the biggest resource hog. Next would be Face Recognition. Smart tagging seems to occur very quickly and can be very useful for searching your media by content.
Finally, if you want to investigate why your hard drive filled up and to make sure you have deleted all traces of whatever it was, there are a number of free utilities that can help you figure it out. I use TreeSize Free but there are a number of other such utilities.
I tried making a new catalog with only the folder that contains the photos I want included in the slideshow. But since that folder is in OneDrive, the app checked OneDrive and started importing ALL the media from OneDrive. I tried unchecking OneDrive but as long as the folder I wanted was in OneDrive, the app would not let me just choose the subfolder. So...I copied the subfolder with the photos for the slideshow to an external drive and got the photos imported that way. I started the slideshow creation process, which looked like it would take a while, and went in another room to do other things. When I came back there was just a play button. I clicked it and a finished slide show started called "Memories 2019 2020" with some hoaky country music and fades that were totally inappropriate. I give up. This application is not for me.