Hi @Anonymous User
Unfortunately you can't watch Freeview channels with the nowtv stick.
The only branded nowtv device that supports over the air Freeview channels where you need to connect a TV aerial into the back of the box, is the first generations nowtv smart box like shown in the picture below.
With the nowtv stick the only teresterial stuff that you can watch is via the BBC iPlayer App, ITV Hub App etc (but this doesn't cover all the live Freeview channels available on the Freeview platform).
@Anonymous User The only smart box which can get Freeview is the one shown in @schnapps ‘s post above yours. Bear in mind though, that it was discontinued a couple (or more) years ago. You might find one on ebay, but it will be used and horribly overpriced (I saw one recently listed at £145). If you want one box for both Freeview and NowTV, then a Youview (not Freeview) box is your best bet if you can find one.