EndNote is a very robust citation management system, and works best with a traditional word processing suite. Pages is designed for collaboration, and creation of eye-catching documents. Pages is great for creating charts and ePUB documents; however, Pages is not designed for academic papers. EndNote will have a different interface in Pages, than it does in Word for Mac.
EndNote will allow you to use Cite While You Write to add citations to Google Docs; however, you will not have the functionality of the Client version. For example, you cannot specify inserting a citation without Author. Add EndNote Cite While You Write add-on in Google Docs via Marketplace. EndNote knowledge base instructions are at https://support.clarivate.com/Endnote/s/article/Google-Docs-CWYW?language=en_US