Is there, perhaps, a mandatory field that you have left blank? Just go through all the fields in that particular page and fill in all the mandatory ones.
If that doesn’t work, try reloading the page.
Even if that doesn’t work, delete all the cookies and cached files from your web browser and reload the page before you try again.
Even if that doesn’t work, contact CS.
Scroll up the page and look at the quesions with an asterisk (*) on the left. They are mandatory fields.
The only mandatory fields on the “professional info” page are “Your occupation” and “Skills” so just put something in those fields.
Occupation can be just like “Graphics & Design” from the video so maybe it doesn’t need to be the off-Fiverr occupation. It says to “select your area of expertise” for that.