K8up (v2 or later) officially only supports recent stable Kubernetes versions.
K8up v1 (not maintained anymore) supports legacy Kubernetes clusters such as OpenShift
3.11 (Kubernetes 1.11).
See the Repository which upstream Kubernetes version is supported.
K8up is only built, tested and supported on Linux. The only supported CPU architecture is currently x64 (otherwise known as AMD64 and x86-64).
In v2.x, we added Docker images for the AArch64 CPU architecture (otherwise known as arm64). These builds are currently provided on a best-effort basis without further testing or support.