I looked all over the web and found some links to this but it was not easy to find so i thought i would write a little article about it.
You will see this error:
Abort class-pclzip.php : Missing zlib extensions
This is because in the file class-pclzip which is in your wordpress directory
wordpress looks for gzopen and now in php that is called gzopen64 so just find all occurances of gzopen and replace it with gzopen64.
Now you can install plugins and themes again. Good luck and hope this helps others.