I mailed on HOTE@adobe.com and my issue was resolved by the support team. Seems like some issue at their end.

Hi,I am not able to login to Campaign Client Console. My credentials are being denied, although they are valid till 22nd April, 2019. Also, this is not the first time I am logging in - The same credentials were working fine till yesterday evening IST; I had been using them for past couple of days su...