I want to develop several demonstrations to publish on my university as additional study material, which package of Wolfram Mathematica should I buy to be able to publish my code and everyone be capable of running it on Wolfram Player (CDF)?
Hi, this page should answer your question, https://www.wolfram.com/wolfram-u/introduction-to-notebooks/
Mathematica produces notebooks and has the cheaper option, however you can try all Wolfram packages as demos to see which one works best for you, including wolfram cloud.
In version 12.2 of wolfram language there will be new "form notebooks" feature, which will allow students to interact with your teachings directly, this video explains the new features
Wolfram Clould allows you to create and web-present notebooks using only a web browser (your subscription to Mathematica is required to use it). I consider it an effective way to publish a demo.