Can’t find how upload embed code with Block system system

Thanks, If I knew I would not be posting. I’ll tell you what I know:

Before, the block system, in classic mode, I go to the Libsyn website and upload podcast there, and then I copy the embed code, which I then paste in the text mode of classic editor.

With block system I cannot find the “switch” from Visual to text. I just posted about that but no one has an answer to far.

I did find this link, where guy says to click the html bottom, but i cannot find that either, hence my post.

….. custom html from guys post. I cannot find it in wordpress, I’ve looked three times: (and if I can, not even sure correct solution, just one guys random post on embedding code

https://clickwp.com/p/embedding-podcasts-in-wordpress/