That depends entirely on how you’re running the nodes. If you’re running the nodes as a systemd service then the terminal does not need to remain open.
As ADAfrog explained. Sync overnight. Give it a time.
For the other point. Use tmux. With tmux you can close your terminal and shut your workstation down and the session won’t close till you open next time.
I’m attempting to set up my first stake pool and I’m currently experiencing this same error message. What do you mean by letting the node sync? Does that just mean to leave my node running, or is there a specific process that I need to run to sync?
yes, just let your node run. Eventually it will sync to the top of the chain, you can verify if it synced by looking in places like:
All of these places will show the latest information about the chain. For your purpose (verifying syncronisation to top), just look at your current epoch, block height and slot number.
After syncing the blockchain you may encounter a similar problem. In this case, try to explictly set the era which you want to query like this --mary-era (if available by the CLI comand you try to use)