When a staff tag is used to unlock the Cashless POS application if a pop up says "This user does not exist" it is a configuration problem on the back office.
It is necessary to check :
- That the staff tag has the rights to access the profit center of the terminal
- That the terminal is on the right profit center
- That the Cashless Sync application is well synchronized
If after that nothing works, the staff tag is potentially defective. In this case just use another.