Thanks for participating in the product preview. The team is aware on this and since this is a beta client, it may contain issues as we continue working to improve the app. Here are the options going forward.
Option 1: Choose to install either Office 2016 Mac Preview OR OneDrive for Business Mac Preview on your system.
Option 2: Clean up the cache every time you start the ODB process
Close OneDrive for Business Mac Preview
Delete ~/Library/Group Containers/UBF8T346G9.Office/Microsoft/AppData/Microsoft/Office/15.0/OfficeFileCache
NOTE: ~ is shorthand for the user’s home directory in the file system.
Restart OneDrive for Business Mac Preview