.
Without looking at the library, I suspect that the text() method expects a string. const char* is a pointer to the first element of the string (and the last element is the null character.)
Is there another method in the library which can print a single character? This will let you display a count 0-9
Look into using the sprintf() function to 'print' the counter into a string in memory, which you can then use with the text() method.