Check these settings to make sure you're able to see other players in MSFS 2024:

Flight Conditions

1. On the Free Flight map, click Flight Conditions in the top right.
2. Choose Custom for weather and time. Pick whatever time of day and weather you want.
3. Make sure Multiplayer is set to All Players.

Online Settings

1. Go to Settings → Online → Enable Multiplayer
2. Select your desired multiplayer server. You'll only see people who also have selected the same server as you. I use West USA.

Enable Air Traffic 

1. Go to Settings → Graphics → Global Rendering Settings
2. Make sure Air Traffic is not off. The higher this setting, the more unique planes will be shown in the game. If it's off, no planes will be shown.

Enable Traffic Nameplates

• To see the names of other players in game, you need to turn on Traffic Nameplates. You can do this in Settings → Flight Interface.
• If you have a keyboard, the default shortcut to toggle nameplates is ALT+2. You can customize this shortcut in Controls settings.