The HypoVereinsbank only supports mobileTAN method and chipTAN method via HBCI / FinTS.
So far the appTAN method is not offered for the HBCI API.
Please proceed as follows to solve the issue:
1. Ask the bank to enable the mobileTAN method or the photoTAN method for your access.
2. To enable the new TAN method in Outbank, please update the configuration: 'Settings' > Credentials > select HVB > 'Update Configuration'