Исправить ошибки в проекте IoT Cpp esp8266

What needs to be done: develop an EXE application in C++; create a modern graphical interface according to my design; implement the program logic; ensure stable operation on Windows 10 and Windows 11; provide the source code in Visual Studio (.sln, .vcxproj). I already have: interface design (screenshots attached); program operation concept; list of features to discuss with the performer. Requirements for the performer: confident knowledge of C++; experience with Microsoft Visual Studio; experience in developing Windows Desktop applications; neat and readable code; willingness to maintain communication during development. Please, in your response send: examples of your EXE programs; experience with C++; estimated completion time; cost of work.

Good day It is necessary to create a module that will work with the Firebird database in C++ for selling products. There are examples of ready-made solutions and a description of the module's functionality. Main functions: authorization, selection of products on the screen from groups/subgroups, transition to the cart, payment by card, and printing the receipt. The program must work on Windows 10 and above, using the existing database.