cannot add 4th work or school account

We have the difficulty with one customer that we only have three work or school accounts (Microsoft 365)‎

‎in the Windows 10 PC!‎

‎If we want to create the 4th account, we always get the error message CAA5010A (see appendix)‎

‎Here there seems to be a limit for creating the accounts!‎

‎We would like to increase this limit to 4 or 5!‎  

Error msg: A problem is occurred

the device cannot be registered to the windows account; Your access to organization resources is possibly restricted