As mentioned Wikitude does not offer any content services. Also as working with existing APIs to fetch POI data has no direct technical connection to the SDK itself and the approach which data you're using is totally up to you, we can't provide any 'How to guide' for how to get the data into the SDK.
The best is to get a deeper understanding on the geoAR features of the SDK and how you can work with POI data on the SDK side. Also check with Google Places tutorials and online how to work with their API and how to get the POI data.
I hope this helps.