There is a similar post and since February it did not receive any answer: https://www.researchgate.net/post/Is_there_any_EEG_signal_database_of_Alzheimers_available
Far from neuroimaging databases, i did not find any 'disease database' with EEG data. Since there are some works on Alzheimer and EEG, you can ask the authors for info on that. Perhaps they can help you more rapidly.
as far as I see, the link which you had provided earlier doesn't lead to any dataset. Would you mind updating me, if there is still such EEG dataset for AD patients available. I thank you in advance.