If overflow scroll is wanted the button group needs to be wrapped in an overflow nav component
<div class="sds-btnGroup">
<button type="button" class="sds-btn -btnSecondary">
<span class="sds-btn__text">button text</span>
</button>
<button type="button" class="sds-btn -btnSecondary">
<span class="sds-btn__text">button text</span>
</button>
</div>
<div class="{{ namespace }}btnGroup{% for mod in modifiers %} {{ mod }}{% endfor %}{% for mod in classes %} {{ mod }}{% endfor %}">
{% render "@btn-secondary" %}
{% render "@btn-secondary" %}
</div>