Pointing Custom download of Foundation to a CDN #15532

We use a custom package of v6.5.1 of Foundation (for some reason the later versions did not work on our website).

Having used it for a couple of years, we decided to use a CDN to host our static javascript and css files. Unfortunately, when we point the <script src....> to the CDN, we get errors along the lines of "foundation webpack_require is not defined"

Has anyone migrated a custom package of Foundation to a CDN?

Not sure what we need to change.