Federation's metadata URL
To check registrationAuthority field input the value here

Entities SHOULD have language variants of certain elements. All entities SHOULD have an English variant and a local one. You may set a number of language tags which will be then treated as local languages and the validator will issue a warning if none of these languages appears within language variants of the entities. You may set the language to "en" so that no warnings are generated if no other language variants are present in the entities.
If no language tags are set, the validator will complain only if no non-English variants are found.
Select your language tag click to add next language tag
or
skip local language checks
Metadata URL contains only one entity
 no EntitiesDescriptor tag and matadata not signed
We check all MUSTs and SHOULDs from the eduGAIN profile requirements and recommendations (see eduGAIN Policy Framework).

Checking metadata...
ArnesAAI Slovenska izobraževalno raziskovalna federacija - Slovenia
URL:https://ds.aai.arnes.si/metadata/arnesaai2edugain.signed.xml