Wifi internet is free for IHG Rewards members who book through an official channel (like the IHG website).
The major hotel groups like IHG have used free wifi as a way to incentivize guests to book directly instead of using online travel agencies (OTAs) like Expedia. When booked directly, the hotel doesn't have to pay a commission to the OTA.
If you look at the Features page of the hotel website, you'll find the following: "Standard Wireless internet service is free for all IHG Rewards Club members"
Source:
https://www.ihg.com/holidayinn/hotel...tail/amenities