Comment 1 for bug 1934522

For non amd64 workloads you generally have to specify an arch constraint. "juju deploy myapp --constraints arch=arm64"

This is required because with Charmhub there are different charm packages to download based on whether it is amd64 or arm64, and rather than trying to guess we just mandate that an architecture be set, but we might as well have a default for the common amd64 case.