You are able to view all PDF in the latest versions of Safari but the editable fields will not be visible on your Mac or Apple device while using Safari.
If you want to complete an editable PDF using your Apple device you will be required to download Adobe Acrobat reader.
Please visit the below sites and check system requirements
https://get.adobe.com/uk/reader/
https://helpx.adobe.com/reader/system-requirements.html