From several attempts I realized that awesomeBB is a little harder to customize in the subforum but not impossible.
Demo


Step 1:
Admin panel / display / templates / general / index_box and we are looking for:

Code:

{catrow.forumrow.L_LINKS}{catrow.forumrow.LINKS}

Then we replace it with this one:

Code:

<div class="subforum">{catrow.forumrow.L_LINKS}{catrow.forumrow.LINKS}</div>

Step 2:
Administration / display / colors / css panel

Code:

 
.main-inner{
    padding: 6px;
}
 
.subforum{
    font-size: 0px;
}
.subforum a{
display: none;
}
.subforum a.gensmall{
    display: inline-block;
    float: left;
    width: 30%;
    margin: 1px;
    border: 1px solid #ddd;
    padding-left: 6px;
}