Hi,
Adobe Target is a fully independent Adobe product that can be integrated with any other platform. Therefore, you can definitely integrate it with an on-premise AEM. The difference is that when you integrate it with AEM, which is another Adobe product, you can gain extra benefits such as the option to export XF.
How to integrate Target will depend on your specific scenario and available tools. The preferred method is to integrate it through a Tag Management system, with Adobe Tags (formerly Adobe Launch) being the most common one used. However, you could also integrate it using GTM or another tool.
You can learn more about the options for installing Target here:
https://experienceleague.adobe.com/en/docs/target-learn/tutorials/implementation/2-1-intro-to-target-implementation
https://experienceleague.adobe.com/en/docs/platform-learn/implement-web-sdk/applications-setup/setup-target
Hope this helps