I suppose the link works at the time.
Now we are supposed to use the API v2 to create page, so to follow this doc: https://developer.atlassian.com/cloud/confluence/rest/v2/api-group-page/#api-pages-post
You can see on the right column a basic example with Forge.
The API doc is very terse, I encourage you to check others people post, like this one: Confluence REST API v2 — Create page with atlas_doc_format representation - #2 by KingChungHuang to better understand what the payload should contain.