AWS Connect Voicemail Template Fails to Deploy

I am trying to install voicemail template (https://docs.aws.amazon.com/pdfs/solutions/latest/voicemail-for-amazon-connect/voicemail-for-amazon-connect.pdf) on my aws account although I am getting the following error while deployment which causes the whole deployment to fail:

CREATE_FAILED: Embedded stack arn:aws:cloudformation:eu-central-1:######:stack/AWSVoiceMailStack-VoicemailStack-#######/###### was not successfully created: The following resource(s) failed to create: [CognitoUserPoolUserPool, ApiGatewayRestApi, ApiGwAccountConfig].

I've tried to set a totally unique name on the userPool prefix, as this was a common issue with this template but still didn't work. Unfortunately I don't know what other info could be helpful about it but I can provide it later.