@HEVABUNY Downloading on a Mac can be tricky sometimes; I have one too. But you should be fine if you get just the right combination of steps. I tried downloading Hidden Springs a minute ago, and it worked fine for me. Here's what you can try:
- Use Firefox, not Safari or Chrome.
- Clear Firefox's cache, if you haven't already.
- Open the launcher, but it's not necessary to login (I didn't, just now).
- Sign into the store, and go to Hidden Springs's product page directly: https://store.thesims3.com/hiddenSprings.html?categoryId=12642§ion=UpSell
- When Firefox asks you what you want to use to open the download, choose the entry that says simply "The Sims 3" (the base game, not a pack) and has a green plumbob next to it.
- If Firefox is blocking popups, the download will fail. You should get a small yellow banner across the top of your screen to alert you, but you can click on it to allow the store's popups. You can also temporarily change your settings under Preferences > Privacy and Security; scroll down to permissions.
If this doesn't work, remove your entire TS3 game folder from Documents and try again. (Be sure to open the launcher before you try to download; this will create a new game folder.) Once HS has downloaded, you can move it from the Downloads folder inside your new game folder to your old one, trash the new folder, and put the old one back in Documents\Electronic Arts.
And if that doesn't help either, please let me know, and tell me which OS you're using. You're the second person recently to report a downloading issue in macOS, although I haven't been able to reproduce. If this is a pattern though, more information would be appreciated so we can narrow things down more quickly.