If this is the case with you, your IT will block your access to some pages and basically do a very good job! But in order to use the backend at your workplace, you would have to ask your colleagues to unlock the following pages or to add the following domains to the whitelist:
https://us-central1-salesapp-next.cloudfunctions.net (API for sending email and text messages)
Afterwards you should have no restrictions and full access to the backend.
Only Internet Explorer should be avoided in connection with the backend.