If you are attempting to select a tour and the app indicates you must have a paying subscription to access it, you might be logged in under the wrong account or your account subscription may have lapsed. You should tap the profile button inside of the app to check your account status.
If you have selected a tour but when you are viewing it you see all stages but the first one as locked, it might just be that those stages have not been unlocked yet for this account. Stages are a bit like “bookmarks” for a tour. As you reach further points of a tour you can come back and start from that location again.