Hello
@gorgeous-twilight-36263
It seems you tried out an older community contributed frontend - those are not actively maintained by Ory and can be very outdated, so there is no guarantee they work
You can see here an overview of community contributed examples/guides and code:
https://github.com/ory/awesome-ory
I would recommend though to try out the quickstarts and samples from the official documentation, those are maintained and updated and should work without issues.
fwiw Ory can take care of the AuthN/AuthZ part for your Saas, but you will need something extra for payments and likely also api key mgmt