Friend there are several methods I will leave you 2 the first one is direct in the html
<div style="display:flex;">
<p class="mt-5 mb-3 text-black">¿No tienes cuenta?</p>
<p class=""><a href="cuenta.html" target="_blank">Crear cuenta</a></p>
</div>
And the other is with the same div you assign a class and you add the CSS
.alinear{
display:flex;
}
And the html you add the class
<div style="display:flex;">
<p class="mt-5 mb-3 text-black">¿No tienes cuenta?</p>
<p class=""><a href="cuenta.html" target="_blank">Crear cuenta</a></p>
</div>
Both methods are thanks to the display flex property and you use the styles you want, such as padding or margin. I hope it serves you.