Enrico: You can place arbitrary HTML into InDesign with Object > Insert HTML. But as Aaron says: you will need to be careful and test it.
There are other ways to do fancy HTML things, such as custom CSS, as mentioned in this article about adding scrolling text frames:

Adding a Scrolling Frame in FXL and Publish Online

Oh yeah, definitely do NOT use colons in file names on a Mac! Super bad.
Here’s a pretty good roundup of symbols not to use: https://www.mtu.edu/umc/services/digital/writing/characters-avoid/
That’s not 100% accurate, because they’re concerned with files being on a web site (so, symbols to avoid in URLs). But I would avoid slashes and colons for sure.

Great! I’m glad that worked. :-)

Oh, I should have pointed to that… sorry… yes, the conference has “post-conference passes” which you can find here: https://creativeproweek.com/online-2020/register/
Nigel’s session was during 3 minutes max for InDesign, on Wednesday.

Argh… sorry about that, Tom. Thank you for letting us know. Deleted now.