A quick look at the documentation shows where the author got this wrong. When you receive the notification you need to set the tooltip text into the buffer as follows:
// this is where the tooltip text is set
sprintf_s(pGetInfoTip->pszText, pGetInfoTip->cchTextMax, "Some helpful tooltip");
Note, this is an over-simplification, and you should check the documentation to ensure you are following the rules.
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