Clock and tempo are two very different variables.

Clock is to synchronise the A/D and D/A conversion and internal sample rates in apps and devices to one physical master clock in the system (running at several MHz), to avoid needing drift correction (where samples have to be added or dropped between devices because the local clocks on their own never run exactly the same). So clock needs to be a constant. And you still have to set all apps/devices to the same sample rate (e.g. 48kHz).

Tempo is the time base of the song (e.g. bpm) which is set separately from the sample rate obviously. Most likely the inner works of the device or app will then calculate the exact timing as a fraction of the clock rate, and if both devices or apps do that with the same algorithm and accuracy then with one master clock and everything set to the same tempo it may have that sync'ed too, but no guarantees. And you still have to set all apps/devices to the same tempo and timebase (in bpm/fps/samples/seconds). And tempo can be variable too.