Normally, SPD61 or C61 are compatible with some APPs which supports connecting speed sensor.
It has been tested that Wahoo fitness ,zwift APP ,Runtastic Road Bike APP are compatible with SPD61.
But Runtastic Road Bike APP can't be connected with a speed sensor and a cadence sensor at the same time.
It has been tested that C61 or SPD61 could be connected with Polar v650.
But it is not supported to connect with C61 and SPD61 at the same time.
A short video for connecting C61 with Zwift APP.