Hi Anat,
Sorry to hear about the email syncing issues. Usually, this happens if your Outlook app isn't syncing properly or the account settings are off.
First, check your internet and that the Outlook app is up to date. Then, open the app and ensure you're logged in with the same details as on your computer. If it is, try clearing the app cache and restarting your phone. Also, see if sync is enabled in the app settings and that battery settings aren't cutting off Outlook in the background.
If that doesn't do the trick, let me know if new emails appear on your computer but not your phone, or if it's happening both ways. This’ll help to figure out if it’s a device or server problem.
Best,
Rez