There must not already be such an account. If there is, please delete it first.
Or Do you want to sign in AxCrypt app with different email address? If yes,
Just clear all the AxCrypt app local cache files via File | Options | Clear All Settings & Restartor clicking the Reset button in the sign in dialog. Then the AxCrypt app will get restarted like a new app installation. Now provide your AxCrypt account credentials to sign in with the AxCrypt app.
If the above does not help, please provide detailed information about the issue and write the email to email@example.com