Employer monitoring data usage

Hello there, so i've been working at this company for a few weeks now it has over 500 employees. I recently connected my personal phone to their wifi, i didnt put in a username, just a password. My question is, is it possible for the IT to monitor my activity on my cell phone? And would they be able to identify me through my cell phone or it will be ambiguous for them? Thank you

 

All network devices have a MAC address that uniquely identifies it. When you connect to WiFi, it takes that MAC address and keep it, and give you an ip address. So if necessary they can find you.

Many companies use a proxy server that records and filters web content. They can see where you went to, and use the MAC address to identify you.