JSFiddle - React, Tailwind, and code Playground

HTML

<body>

<form action="" name="f1">
	Password : <input type="password" name="senha1" size="20">
	<br>
	Confirm Password: <input type="password" name="senha2" size="20">
<br>
<input type="button" value="Validar" onClick="validarSenha()">
</form>

<form action="#" method="post" name="cadastro" style="display:none">

 <hr>

	<fieldset class="grupo">
           <div class="campo">
               <label for="nome">Name</label>
               <input type="text" id="nome" name="nome" style="width: 20em" value="" />
           </div>
           <div class="campo">
               <label for="cro">CRO</label>
               <input type="text" id="cro" name="cro" style="width: 5em" value="" />
           </div>
	</fieldset>
</form>

 </body>

JavaScript

function validarSenha(){
	    senha1 = document.f1.senha1.value
	    senha2 = document.f1.senha2.value
 
	    if (senha1 == senha2) {
		alert("PASS OK");
                docuemnt.getElementbyName("cadastro").style.visibility:"visible";
            }
     
	  else
		alert("PASS KO")
        }