How to modify AEM configuration in order to be supported by IDP

When I send a request to IDP， the status code is 405（Method Not Allowed）.  I am new to saml, who can help me to solve this? It is the POST method, maybe the IDP needs GET method?

No error in the saml.log, what I said it is all.

I have tried this method, but it didn't work

15.12.2022 14:55:56.039 *INFO* [qtp2102147594-25673] org.apache.sling.auth.core.impl.SlingAuthenticator getAnonymousResolver: Anonymous access not allowed by configuration - requesting credentials15.12.2022 14:55:56.049 *WARN* [qtp2102147594-25673] org.apache.sling.auth.core.AuthUtil isRedirectValid...

The IDP needs a xml file

The IDP needs SAML metadata(SP), anybody knows what is this? And where can I find it? 

The default textarea is too large. How can I modify the size of the textarea by some fields? Is it possible? Or I must overwrite it and use js to modify it?  

Are there any specific examples？

Are there any other detailed tutorials on CRX2OAK tool?