Does Visual Studio 2017 Community (.NET Framework 4.6.2) support Oracle 8i
I don't have an 8i database handy to test. If you care about your data it'd be wise to upgrade to a supported version of Oracle ASAP. The last version of Oracle client that can connect to Oracle 8i is an Oracle 10 client (and you need to be on Oracle 8.1.7 server-side).

If you can find an Oracle 10 client install (either full-fat or the instant client), then you might be able to get it to work. - Phil

The article referenced in the question is rather bad. Listed prerequisites are wrong/outdated (was even in 2015), it does not properly use the tnsnames.ora file, and does not consider 32/64-Bit topic.

See my answer to Does ASP.NET MVC5 support Oracle 8i on Stack Overflow. - wernfried-domscheit