Create Subnet Group

aws memorydb create-subnet-group
--subnet-group-name mysubnetgroup
--description "my subnet group"
--subnet-ids subnet-0e0fd31733061237d subnet-0c96245f8e4d94ed6
--query SubnetGroup.ARN
--output text

Dont use the default vpc. create a vpc with subnets

Create User

aws memorydb create-user
--user-name andrewbrown
--access-string "on ~* &* +@all"
--authentication-mode Passwords="Testing12345678901234567890!",Type=password

Create ACL

aws memorydb create-acl
--acl-name "new-acl-1"
--user-names "andrewbrown"

Create Cluster

aws memorydb create-cluster \
--cluster-name my-new-cluster \
--node-type db.t4g.small \
--acl-name new-acl-1 \
--subnet-group mysubnetgroup