There are dogs that do not know each other and have never seen each other before, distances must be kept between them to respect the spaces of each of the other participants: there are those who are more shy and those more fearful, the respect first of all.
Covid aside is the first thing any dog educator will tell you, i dogs have an intimate, individual, social and public zone it will be up to them to decide which of these he can be approached.
It will be a discretion of the educator find the right and safe time and place with respect to the context if and when to leave them free
Need respect the local flora and fauna, we are just guests, for the animals that live there it is their home and they should not be disturbed or frightened. The excrements must be collected not only for education but because wild animals are not vaccinated and external components could cost him his life.
Each owner is legally responsible for their dog's acts.