As you might have worked out by now, for most songs you can just change the time signature and it will play (although some styles will not play in some time sigs, like Swing 3/8) without having to change now many spaces are within each measure. The player will look at the time sig, spacing of the chords and how many spaces are in the measure to work out where it will play the chords. You might have to use 5 spaces in some measures, other times, perhaps a couple of spaces for a measure where there is only one chord should work. 5/4 will work with 4 spaces. Try different placements of the chords in different spaces within the measure. You will get errors on pressing play if the player does not know what to do.
There is no rhythm notation input the player knows, so the player is a bit limited if you need a specific rhythm.