How can I specify a database connection while using "/oauth/token" API for authentication

Hi folks, I have two database connections ( one is the default ‘Username-Password-Authentication’ and the other is ‘admin-database’ ) for two sets of users. I have created two different applications “A1” and “A2” (both are of the type “Regular Web Application”) to authenticate them. This is all under one tenant.

“A1” has access to “Username-Password-Authentication” only and “A2” has access to “admin-database” only.

When I use the “signup” API from A2 and create a user in “admin-database”, the user is created.

But when I use the “/oauth/token” API to get an access token, it gives the following error –

{"error":"invalid_grant","error_description":"Wrong email or password."}

Can someone help me understand why?