old versions of Articulate

I have been producing modules for a client who is using a very old system. Previously I published the modules as Flash, and this worked in their system.

Publishing as html5 does not work in their system. As per one of your support threads, I opened a module that had previously been done and was able to publish with Flash fallback, but even that does not work for them now.

I thought if I was able to get a copy of an old version of the program (say Articulate 2) we could try publishing with that? Is that a possibility?

This is what they have sent me:

Just wanted to let you know that we have tried loading all the modules & unfortunately, they are not working as expected. We got in touch with the vendor who provided us replacement for Adobe Flash & they have told us that we are using WebKit 7533.19.4 which is very old & not able to support HTML5 format. The vendor is asking if there is a possibility for you to prepare the package in older version of HTML to resolve the issue.

I understand the answer is for them to upgrade their system, and have advised them of this. However they are a longstanding client and I would like to assist them keep stuff working if possible in the meantime.

Can anyone offer any advice?