I had LR5 on a 2009 Mac and moved it to a 2019 running Catalina and it won't open. in the bottom menu it shows up as a ? for some reason. I downloaded a trial version of a competing software and it was able to open all my pictures from one of the folders I had created in LR.
Will LR open or do I need to upgrade to CC or Classic, and if so why is my other folder able to be opened and used.
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I do not know what you mean by- "other folder able to be opened.."
If you are referring to image files, then yes you will be able to load them onto the new computer. But all the work you did using Lightroom 5 won't be there because that was stored in the catalog that was part of Lightroom 5 and was not applied to the images. So images will be in their original state that they were in when they were first downloaded.
If you can add images to the new computer in the same file structure they were in on the old computer, and then bring the catalog that you were using in Lightroom 5, Lightroom Classic has the capability to upgrade that catalog and then all of your work will still be intact.