Verotel in my country has a VERY BAD REPUTATION, you look carefully.
It is similar to PayPal but when you try to withdraw the money they put a lot of obstacles.
I would not buy a plugin for 79 USD from an author who is not active in the forum, who has only published one plugin and who has no comments, but if you have knowledge of PHP and really need it, maybe it will serve as a basis to modify it and update it.
At least write to the author to see if he continues to work with OxWall.
Surely the communication protocols with the bank will have changed, 4 years is a long time in computing.
It is better for you to trust proven developers like ArtMedia or Senior Developper, for example.
I don't understand why there are plugins like this in the store and others that worked perfectly and had a good reputation have been removed ... :(