This is the reproducer for virtual machine with Ubuntu 16.04.1 LTS Live CD (via try Ubuntu):
snap --version
# snap 2.0.10
# snapd 2.0.10
sudo apt update
sudo apt install --only-upgrade snapd
snap --version
# snap 2.29.4.2
# snapd 2.29.4.2
snap install cloudcompare
cloudcompare.CloudCompare
# cannot create lock directory /run/snapd/lock: Permission denied