Provisioning an instance

Like every browser control panel int he world this one is awful.

Find and select "instances", add new instance and keep everything "always free eligible" 

Image and shape

Image: 
Canonical Ubuntu 24.04 Minimal aarch64

Shape:
VM.Standard.A1.Flex 4 CPUs 24 GB RAM

Add SSH keys

Save the generated private key

Boot volume

Specify a custom boot volume size to 200 Gb (Max for always free resources)

That should be enough! Always free resources are scarce and you could get the annoying out of capacity message. 

To try and go around this, switch to a pay as you go account and / or make a script https://bestofphp.com/repo/hitrov-oci-arm-host-capacity that will spam oracle server each minute.