oAuth Custom Service with MVC

[slSoftware]

Hi All. In my e-commerce web application, im using one of finance application to transfer invoices, therefore i have to use there o Auth api service and Authenticate from them. Can you please share some sample for create custom oAuth service which will open as Pop-up and asking the credentials...etc. Same time i need retrieve the token from them. Thanks

[Wendelius]

Do not cross-post questions. You have already asked this at Custome oAuth Service[^] so stick to one question and be ready to provide more input if needed.