Hi @Ava Tomlinson
There is no native support for single sign-on technologies in Reporting Services. If you want to use a single sign-on technology, you must create a custom authentication extension.
Official documentation for custom identity extensions: Configure Custom or Forms Authentication on the Report Server.
I also found this link for you: https://aeacr.dynu.net/sqlservertip/4988/sql-server-reporting-services-custom-security-with-single-signon/.
Hope these can help you.
Best regards,
Aniya