Hi there and welcome
It is a standalone program and if you just need to open the files for now, then get the demo (trial version of quark) which you can get here
It allows you to use it for 3 days. then you would need to purchase it
If you have any problems, or would like any additional information or assistance, please do not hesitate to let me know.\
Else if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.
do you remember which version of quark you made the files with?