I wrote also the whole documentation for Zeus https://docs.zeusln.app/. Where I put more details about how to be used, because Zeus can be used in many ways: as a node management app and also as a lndhub account interface, to be used as a normal LN wallet.

If you used Zeus with a lndhub account, the channels management is done by the custodian of your account. If you used Zeus with your own LN node, then you must start open channels with both liquidity (inbound and outbound) as @Wumbo told you very well.