Managing permissions and login credentials to access Microsoft Advertising accounts
It seems that your account was suspended due to policies related to account verification and usage. Microsoft Advertising may suspend accounts for various reasons, including inactivity or failure to complete the verification process satisfactorily. Even if you did not run any ads or campaigns, the act of creating an account and importing campaigns could trigger a review process that led to the suspension if there were concerns about compliance with their policies.
For detailed reasons behind your account suspension, it is advisable to discuss this further with your Account Manager or Microsoft Advertising support. They can provide specific insights into why your account was suspended and whether there are any options for reinstatement.
References: