I thought this was interesting: I downloaded TOS on Mac, unzipped, and immediately fired up from right there in my ~/Downloads folder (that was my first mistake -- proper would have been to first move the unzipped folder and all its contents to ~/Applications on Mac, I think). Once launched, of course it created the workspace right there as a subfolder.
I toyed a bit with a sample project, added some components, and successfully connected to Microsoft Access (w00t!) on my Mac (w00t!) without any additional anything outside of the Talend UI (w00t-w00t!). Of course some new components/plugins had to be downloaded along the way.
I thought about changing things around, but when I saw that merely moving the whole thing to the ~/Applications, the default workspace was, nonetheless, still in ~/Downloads. I later did the proper "move workspace" in Preferences, and this worked to a degree. Then, once I started setting up a new project (the same one.. had lost my earlier work in "the move"), I noticed a couple of the "ucanaccess_net" plugin folders had spawned in my ~/Downloads folder!
Any ideas what to do about this? Or just ignore, count my lucky stars that Talend has matured so nicely over the past ~7 years, and move on?
What's your Operating System on Mac?High Sierra? Could you please indicate which talend build version you are using?