Hi Joshua, In order take advantage of the adaptive form technology (assuming this is what you mean by "adaptive fields"), you would need a server license for AEM Forms (OSGi), or AEM Forms JEE. The tool formerly known as LiveCycle Designer is now referred to as Adobe AEM Forms Designer. It can still be used to design dynamic PDF Forms which are supported in Adobe Acrobat DC Pro, or Adobe Acrobat Reader DC. The server license for AEM Forms, which is inclusive of all the legacy LiveCycle server based services and also includes a host of new services, such as mobile forms, HTML Workspace for user interactive workflow participation, Adaptive Forms, and Interactive Communications to name a few. Adobe Experience Manager Sites is a separate license from Forms. You can find more detail on AEM and Forms here at [1].
At the bottom of the page, you can request a demo, and likely a trial by calling that number.
Hope that helps.
[1] See what Adobe Experience Manager can do | Adobe Experience Manager