Recently got Spore again, using a fresh install of both Gog Galaxy 2 and the Spore Collection. After installation, when I went to run the game, it gave me error 1004, but the data folder is there, and even after a verification of the files, it still couldn't find the data folder.

If you are comfortable running "regedit" you can check here to make sure paths are set correctly:
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Electronic Arts\spore
This is for 64bit windows.
Remove the WOW6432Node if you are running 32bit windows.

datadir should be something like D:\GOGcom\SPORE\Data
The D:\GOGcom part may be different depending where you installed it.
installloc should be D:\GOGcom\SPORE, again, the first part may be different.
You can also check the expansions sections as well.
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Electronic Arts\spore Creepy and Cute Parts Pack
DataDir should be something like D:\GOGcom\SPORE\bp1content\
Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Electronic Arts\spore_EP1
DataDir should be something like D:\GOGcom\SPORE\DataEP1\

Note: D:\GOGcom is where I install all my GOG games, be it galaxy or manual install backup downloads. Never install in Program Files due to changes in security Windows has added that break lots of things.

Had the same issue. Checked registry information, it was all correct. After messing around with things for a while (such as experimenting with whether spaces or other characters in the directory structure were messing things up) I finally tried reinstalling on C: (rather than D:) and this worked.