Best AnswerThis help article may be of some assistance.
It's difficult to offer any advice without knowing the exact problem you are having. Are you able to find the weather app in the fitbit app gallery? What happens when you press the pink install button? Also confirm that your tracker is connected to one of your devices via Bluetooth, it's also best to turn off Bluetooth on any other device which might be trying to connect to your tracker.
Best AnswerI use the mobile app myself, so the following is for that.
Press the account tile in the very top right corner of the app, then tap on Ionic in your listed devices and the tap on the apps tile. From here you should have my apps and all apps, tap on all apps. You should then be able to browse the app gallery.