According to this link, MacOS Pages will allow you to create a reflowable epub instead of a fixed layout epub:
See
https://support.apple.com/en-us/HT202066
Your first step to create an epub2 should be to make a reflowable epub in Pages.
Or alternatively,
Convert your Pages file to a Word doc and use Calibre or Sigil to convert that Word file to epub so that you can control creating an epub2 vs epub3.