Do the following to solve the problem
composer network deploy -a perishables-network.bna -A admin -S -c PeerAdmin@hlfv1 -f networkAdmin.card
This creates the network admin card (.card file) - you can import it to get this into the user's wallet.
composer card import --file networkAdmin.card
Lastly, ping the network - the first time its used, the certificates are retrieved:
composer network ping -c admin@perishables-network
this 'first use' will populate the user's (ie admin user identity) wallet in the .composer card store.
You don't need to do your step 5.