Migrate from SSRS 2016 to Power BI Report Server

I recently tried to migrate from SSRS 2016 to Power BI Report Server (March 2018). I ran into an issue where the database would not upgrade. I tried pointing the PBIRS configuration to the existing report server database and I also tried restoring the ReportServer database over a new database that was configured by PBIRS and neither worked. What is the correct way to perform the migration? Microsoft's documentation is very vague on this and I could not get it to work.