Why is box filling my hard drive, lost a document as I had no hard drives space

Same here, since a couple of weeks box is eating my hard disk space. Logging out of box or reinstalling does not solve the problem. 

Really hard to work this way. can you please connect me to Box Support to help solve the problem? 

this is what the box support told me to do

Mac:
Box Drive in File Provider Extension mode doesn't support the ability to configure maximum cache size.  In the FPE mode, macOS manages the caching functionality.
Refer to Modes of operation in Mac to determine whether Box Drive is operating in kernel-based or FPE mode.

1. Open the Terminal
2. Run the command below. Replace Cache_Limit_Here with an integer representing the new cache limit in GB:
   
   defaults write com.box.desktop MaximumCacheSize -int Cache_Limit_Here
3. Quit and re-launch Box Drive after running this command.

This new limit applies only to the Mac user who ran the command. It does not apply to all Mac users on the machine.
To revert the limit, run the following command in Terminal and re-launch Box Drive:
defaults delete com.box.desktop MaximumCacheSize

 
You visit this Article for more detailed information: Technical Information for Box Drive Administrators

Thanks, for your quick response, I work on a windows pc