Zip file on ipad

As you have a more recent iPad and installed version of iPadOS, you should be able to natively access basic Zip-files. Perhaps this Support Page will help:

How to open ZIP files on your iPhone, iPad, or iPod touch - Apple Support

You should note that there are many variants of Zip-files that use unsupported compression algorithms - and as such some Zip-archives will not be accessible using native tools. For these files you may need to install a suitable third-party App from the Apple App Store.

The tags appended to your post suggests that you have an iPad with iOS9 installed. If this information is correct, the installed version of iOS is not capable of opening/accessing Zip-archive files.