I have already facing same issue
I resolved the issue. There are several steps that I had to take.
1. From the dashboard, hover over your page name in the upper left hand corner and select “edit site”. (the dashboard that comes up by default didn’t enable plugins for the underlying site)
2. Go to plugins on the new dashboard.
3. Activate / install Raw HTML
4. Open the webpage in another tab and select “edit page” in the menu bar at top of screen.
5. Select the editing area and notice that three vertical ellipses appear at upper left hand corner at the top of box
6. Click the ellipses and in the dropdown menu, select “Remove Block”
7. Click to edit in html
8. Use <raw> </raw> around your HTML code to prevent WordPress from stripping tags on clicking “Update”