The version I have listed is 1.70.021[2.00MB] and the file size is 1.75MB, which works fine for me. That's the one from the store.
There is also the public version available on Download.com through THIS link. File version 18.104.22.168 file size 7.53MB.You may want to try that one. Be advised that Download dotcom may have bundled other crapware with it, check all install options carefully.
You should not need Impulse in any form to install or run a free app. I'd fire off a letter to support even though officially, LS is no longer supported, The installer should still work.