The key to whether or not the other party has the right is: the square in front of the supermarket, whether or not its ownership (right to use) belongs to the supermarket.
One, if it is owned by the supermarket, the supermarket has the right to decide, whether to allow you to use;
Two, if the square is a public **** place, you have the right to use. But be careful not to disturb the people;
You can consult the city management department, who owns the square? Take a step back, even if it is owned by the supermarket, you can negotiate with the owner, if it does not affect the operation of the supermarket, the owner should be agreed, the key is that you do not interfere with the normal operation or life of others.