Hmmm. I don't know. I probably wouldn't use that. I am sure it is an effective anti-fungal but I have no idea if it is toxic to birds.
Whereas there is lots of experience of drugs like miconazole to say thy are very safe for chickens.
The antifungals with 'azole' are readily available in...
I would use any antifungal cream (check it has an ingredient that ends in 'azole' - like miconazole and does NOT have pain killers included as they can be toxic to chickens).
I would definitely apply it to the area around her vent. But some sources I have read say you should also give it orally...
I am by no means an expert but it is possible that is vent gleet.
have a look at this.
https://www.bhwt.org.uk/hen-health/health-problems/vent-gleet/
Looks like they are recommending simple anti-fungal cream.