Unable to edit furigana

[Eminib]

I’m creating Japanese flashcard with Anki auto generating the furigana for me on Anki windows.
The guide for me to edit the auto generated furigana is to “enter your desired furigana within 「「」」at the end of the field. For example 日「「ひ」」”

I have tried putting this at the end of the sentence, after the word itself, tried other similar bracket, still unable to edit but instead it just appear in the flash card as normal text

[Danika_Dakika]

Are you sure this is Anki? Anki knockoffs - Anki FAQs

Or is this a custom interface generated by an add-on? If so, which one?

You can find the authentic versions of Anki at https://apps.ankiweb.net/ . In Anki, you can use the built-in furigana notation – Field Replacements - Anki Manual – or just standard HTML.