As second step states. Apply executable permissions to the binary:

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sudo chmod +x /usr/local/bin/docker-compose;

In addition to the comments provided in the question

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sudo usermod -aG docker $USER                  # to add myself to docker group

sudo chgrp docker /usr/local/bin/docker-compose     # to give docker-compose to docker group,

sudo chmod 750 /usr/local/bin/docker-compose   # to allow docker group users to execute it

You might want to try running newgrp docker