I assume from the "Alby node" language that you are talking about Alby Hub. Are you running it as a standalone node, or are you running it alongside an LND instance you already had set up on something like an Umbrel or Start9?

If the former, have you already opened a channel? You cannot receive via Lightning (invoice) if you don't have a channel open that has inbound liquidity. You will first need to receive on-chain and then open a channel, or buy an inbound channel.

In Alby Hub, go to Node > Advanced > Deposit Bitcoin to get on-chain funds into your node that can be used for opening channels.