Is it possible to create new user from external form using REST API?

If i’m not sure if i have misunderstand your question might, yes you need to send a post request to POST /wp/v2/users api. That should do the trick i dont think programming language have issue on this. I believe you should decide how post submitting flow should be affecting.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)