This simply means that you have used up all of your assigned spins in a 'Challenge' format tournament (or used your balance / met the maximum wagering requirement if a 'Risk' format tournament). I.e. the ''blocked from playing'' message means that the game has now ended for you.
The number of spins in a 'Challenge' format tournament is the same for all players, and can be viewed in the tournament console (see below example).
Likewise players are assigned the same balance and maximum wagering requirement in a 'Risk' format tournament (see below example).