A skilled futsal player does not translate to a skilled soccer player. The two games are similar, but ultimately different.
In futsal, sometimes all you need are a couple inches to make a difference, whereas in outdoor you sometimes have a buffer of a yard or so.
First touch is also extremely important in futsal, as that can be the difference between passing a defender or getting the ball immediately stolen. In soccer, a bad first touch has more leeway.
1 on 1 skills are far more important in futsal, as you will constantly clash with one defender. In soccer, passing and working with your teammates is more key. You’ll still need passing and cooperation skills in futsal, just on a much smaller and subtler scale.
The pace is much faster, almost frantic in futsal while soccer can often have periods of calmer play. Stamina is also crucial to soccer, but less in futsal, as the duration of game is shorter and the field is significantly smaller.
All in all, skilled futsal players can play in soccer leagues, it’s just a matter of personal preference. Some like playing both indoors and outdoors, others prefer to stick to one.