A role and an authority are not the same! 

An authority is a legal term: you must have an authority to be permitted to do something on behalf of someone else (e.g. an accounting office or social secretariat undertaking administrative work on your behalf). With just an authority, it will not be possible for your to modify your bank account number with Constructiv.

You will also need a role assignment: this is an administrative step that ensures that someone also has the technical capability to undertake something on your behalf. 
An authority therefore relates to the legal framework, while the role means that someone effectively has the technical rights to undertake something on behalf of your company. 

Further information about authorities