I go to "Edit", then "+", then "</> Markup", choose "Confluence Wiki" then paste this HTML into the Insert box:
<IFRAME WIDTH=1000 HEIGHT=700 FRAMEBORDER=0 src="https://app.smartsheet.com/reports/Hq37MHRXQ2MMjvP4w7r7rhJrv3qf5HfFWh2fWqM1?view=grid"></IFRAME>
It shows up in the preview box as HTML while I expected to see the Smartsheet page. If I proceed, it puts the same HTML on the Confluence page. What am I missing?
Wiki Markup is not the same as HTML.
You need an app that specifically supports adding HTML.
Here is a link to search the Atlassian Marketplace for some options. You'll need to add your own hosting type to the search criteria to narrow down the compatible choices.
https://marketplace.atlassian.com/search?product=confluence&query=html
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