O365 Powershell error during global admin credentials validation

We are using Powershell script for validation O365 credentials (is it global admin O365 user or not). It was working fine for all cases except one. We received an error: 

Connect-MsolService : Exception of type 
'Microsoft.Online.Administration.Automation.MicrosoftOnlineException' was 
thrown.
At line:4 char:1
+ Connect-MsolService -Credential $cred
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (:) [Connect-MsolService], Mic 
   rosoftOnlineException
    + FullyQualifiedErrorId : 0x800488F2,Microsoft.Online.Administration.Autom 
   ation.ConnectMsolService 

Also, we have verified that these credentials are credentials of O365 global admin user, there is no SSO and MFA enabled for this organization.

Powershell module is up-to-date. The script which is executed is next:

'Import-Module Microsoft.Online.SharePoint.PowerShell -DisableNameChecking\n'
'$cred = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList'
' $username, $(convertto-securestring $password -AsPlainText -Force)\n'
'Connect-SPOService -Url "$admin_site_url" -Credential $cred\n'

and we are passing appropriate values in variables.

Is it possible that somewhere in Portal Azure this global admin user has disabled Powershell access for the account? Or this organization disabled Powershell access?