I bought the Misfit Link for a fraction of the cost of other fitness trackers, and my expectations are in proportion to price. Nonetheless, I have deducted a star from this app for the challenge level of setting it up correctly.
If you only want an activity tracker, the simplest thing is to just use it with the Misfit app, and forget about the Link app. If, however, youd like to double-click or triple-click the tracker to control some function while still using it as a tracker, read on.
A Flash can ONLY be used as an activity tracker OR a music remote OR a selfie button OR a Preso clicker OR a Bolt switch OR a "custom button." It cant do them all at once, despite advertising implication. If you set up your activity tracker via Link you can have those extra functions, but its not going to do them all at the same time. First, disconnect your Flash from the Misfit app if youve already connected it (disconnect it from within the app.) After that, go to your phones Bluetooth settings and disconnect the Flash there, too.
Now open the Link app. Go ahead and connect your Flash to it, and select Activity Tracker. The Link app will automatically connect your Flash to the Misfit app as well as to itself. Yay! You now have the function you probably bought the Flash Link for. Now you can set up the double-press or triple-press functions to a) send a "Yo;" b) connect to IFTTT.com for a recipe you can set up; c) Connect to a Harmony home control system; or d) ring your phone. I use IFTTT extensively -- so I have an IFTTT recipe connected to the double-press, and another connected to the triple-press.
Finally, you will get the opportunity to set up your Flash to automatically turn on and show you your progress and the time when you raise your wrist (like an Apple Watch.) Think carefully before you turn this on; you cant turn it off, and it will run down your battery a bit faster.
Now you can edit the tracker in Link to do one of those other functions (selfie button, etc.). It will still track your activity, and you can still sync it with the Misfit app, but you wont be able to see your progress or the time on the tracker itself (unless you turned on the wrist flick thing) until you edit the tracker back to the Activity Tracker function in the Link App. Also, you wont be able to tag activities unless your Flash is in Activity Tracker mode in the Link app.
All this is horribly confusing, and not well explained in the apps as youre doing what youre doing. Worse, the Misfit app offers you an opportunity to set up your tracker with the Link app from the Device page within the Misfit app itself. Dont believe it! It lies! Disconnect your Flash from the Misfit app before you start in with the Link app, as I described above.