Please note that you wrote to the ResearchGate community, not to the RG team. - It seems that this type of emails is no longer available, see https://www.researchgate.net/settings/emails (and see https://help.researchgate.net/hc/en-us/articles/14292900996241-Managing-your-email-settings).
I have to correct myself: The option to receive notifications about new citations is still there (see Rob Keller's reply to https://www.researchgate.net/post/Why_I_havent_received_recent_citations_on_my_ResearchGate_account/1). I had overlooked that. However, it seems that these notifications do not work at this time. Generally, the last notification I received from ResearchGate was of January 13 this year.