When viewing the page for a module, e.g. Mojolicious, on the right hand side of the page:

Distribution: Mojolicious
Module version: 7.87
Source (raw)
Browse (raw)
[download]

This may not render on the right hand side on a mobile browser with the screen in portrait orientation.

However, the manual process is laborious (think about having to satisfy dependencies), you'd essentially be manually downloading/copying and pasting lots of files. Well worth resolving whatever issues there are within your organisation. At $work we have no direct internet connection, however minicpan makes it trivial to maintain a mirror and transfer this into the network via an approved route.

Update: alternatively, metacpan lets you access the source like this: https://metacpan.org/source/Mojolicious.

Do you see how on eg. JSON::PP there is a link in the left nav which says "Source" and a link beside it which says "(raw)"? It's the raw link you want.

Update: marto's reply suggests he sees this nav on the right instead of on the left. Regardless of where the CSS puts it for you a simple search-in-page for "Source" should find it.