As much as I wouldn't wish Oracle Portals and OWC, on anybody, it sounds like what is actually being asked of you. That entire stack is Oracle all the way from OS, to database, to programming language (Java), to web front end. There is no Microsoft in the picture there considering Larry Ellison's "Bill envy".
To learn how to use this monstrosity, you have to pay big bucks to watch the Oracle training videos. As I was doing that training, I was regretting every decision that I made in life that lead me down the path of having to take that training. (By the book, Oracle will not entertain any issue tickets opened if people opening the ticket had not taken their training.) To make matters worse, the video is taught by this teacher who makes the teacher saying "Bueller? Bueller? Bueller?" sound like Tony Robbins. He just invites the mind to go wander -- and in my case, again further regret agreeing to work on that project temporarily.
Suffice it say, I left that group as soon as I could when they were going to make my temporary assignment a permanent one.
Now, on the other hand, if what they are asking for is truly an Oracle database backend, and they don't care that the web front end is .NET Framework, don't bother looking for something that specific. If you already know how to use .NET Framework with SQL, then you know how to use .NET Framework with any other database. All you will need to do is replace SqlConnection and it's associated classes with the other database's wrapper classes. In the case of Oracle, use Nuget to download the Managed Oracle drivers and away you go.