It's not a dumb question. 
You can't track the actual click/tap event on a site that isn't running Munchkin. You can, however, track the subsequent pageview that results from visiting a Munchkin-tracked redirector page, before that page redirects to the actual downloadable asset.
In fact this is the way everyone should share assets. Sending direct links to assets, even from Marketo-generated emails, is bad for tracking.
OK, I'm going to give you the easiest, dirt-simple, this-isn't-the-way-I-would-do-it-but-here-I-am-showing-it-to-you-anyway method.
Add this to the document <head> of your redirector page (which should be otherwise empty). Turn off Munchkin at the page level as you're loading it manually.
<script type="text/javascript">
document.write(unescape("%3Cscript src='//munchkin.marketo.net/munchkin-beta.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script>
Munchkin.init('111-222-333'); // your Munchkin ID and options, obviously!
</script>
<script>
(function(redirectTarget){
var allowedOrigins = [
], // which domains are allowed for redirection
redirectMs = 3500, // how long before redirecting
progressMs = 500, // how long between updates of the "progress meter"
progressChar = '•', // progress character (HTML bullet)
errNoAsset = 'Asset URL not found.', // message when no asset in hash
errInvalidAsset = 'Asset URL not allowed.', // when asset not our domain
progress = setInterval(function(){
if (redirectTarget) {
document.body.insertAdjacentHTML('beforeend',progressChar);
} else {
clearInterval(progress), clearTimeout(redirect);
document.body.insertAdjacentHTML('beforeend',errNoAsset);
}
}, progressMs),
redirect = setTimeout(function(){
var redirectLoc = document.createElement('a');
redirectLoc.href = redirectTarget;
clearInterval(progress);
if (allowedOrigins.indexOf(redirectLoc.origin) != -1) {
document.location.href = redirectTarget;
} else {
document.body.insertAdjacentHTML('beforeend',errInvalidAsset);
}
}, redirectMs);
})(document.location.hash.substring(1));
</script>
Then, to link to your assets, append your asset URL after the hash (#) in the redirector page: http://pages.example.com/redirector.html#http://example.com/redirected.pdf
You can then trigger on the asset downloads as pageviews:
The reason I don't do it exactly this way on my own production sites is that it adds a mandatory minimum delay before redirecting in expectation/hope that Munchkin will load + log completely in that period. The delay above is 3.5 seconds (3500ms) which is okay for, let's say, 99.99% of cases -- but not all. Instead we have a custom Munchkin library (we call it "Munchkin Enhanced") that can ensure the delay is just long enough for the hit to be logged, but no longer. Anyway, this should fit your needs for the most part.
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