Yes it can. Even the Steam version has no DRM. I don't allow Steam or GOG Galaxy to run automatically, and I don't have any problem playing the EE's I've bought from those vendors.
I think you're going to need to give us some more information. Who did you buy it from? How are you launching it? Have you tried running the icewind.exe directly?
I purchased it from beamdog.com. Only the Beamdog icons we're set up on my laptop, so I tried to access the game using them. No, I've never tried using the icewind.exe file.
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You only need the internet to download the game. After that, you play it offline ever after.
Unless maybe you're asking about the Steam version. In which case, this is a Steam question, and I don't know the answer.