ondemand error

[rio lim]

when i try to sign up for draw.io for confluence cloud, i get this error:

"You must signup for OnDemand before you can configure an OnDemand instance. If you already have an OnDemand account please check that it is linked to your current username."

so i click sign up and i got to this mesage
"Welcome back. You can add products to your existing Cloud site from the site administration." 

so i went to site administration as they told me to and i get the same error message 

"You must signup for OnDemand before you can configure an OnDemand instance. If you already have an OnDemand account please check that it is linked to your current username."

[Nic Brough -Adaptavist-]

There is no error message here.

You've created an account, logged into it, and not told it that it has anything to do with your Cloud Confluence.  You need to log into the account that owns your Cloud Confluence, or has been added as a maintainer.