If you look at those "errors", you will see that they are actually just warnings about old-fashioned ("deprecated" means "discouraged and planned for removal in some future version") or badly-written ("strict standards" just means "could be improved") code in the library.
The code will carry on running just fine. However, if this library is not currently maintained, you may find that in future you have to either make major changes to it yourself, or move away to a more modern library.
Check out the error_reporting
ini setting and error_reporting()
function for how to change which types of messages are displayed or logged.