Databricks (Spark) will often try to do things automatically that you aren't explicitly asking it to do. Without your exact dataframe and database table schema, it is difficult to say, but check for the following issues which can result in Spark trying to create a table:
Confirm the table actually exists. Since you've already done this, try...
Confirm the schemas are a perfect match. This is the issue I see most often that causes the CREATE TABLE permission error.
You can also try to log the exact commands being issued to the database to do more advanced troubleshooting, but I've only needed to do this a handful of times.