The master version of the module which has been migrated to controllers has the routes file on a location different from what simple SAML expects (the root of the module):
This week SimpleSAML 1.19 will be released where the location was changed to /routing/routes/, so the location is correct.
You can't use master on SSP 1.18
The master version of the module which has been migrated to controllers has the routes file on a location different from what simple SAML expects (the root of the module):
Actual location:
/routing/routes/routes.yaml
Expected location:
/routes.yaml