I figured it out! My recommendation is not to use these widgets and to do this instead.
If anyone else runs into this, you can use the below for contracts or options:
<a href="https://cart.mindbodyonline.com/sites/[YOUR STORE ID]/cart/<?php echo $contract ? 'add_contract' : 'add_service'; ?>?mbo_item_id=[YOUR PRICING OR CONTRACT OPTION ID]" class="btn-primary btn-link"> BUY NOW </a>
& you can use the following for a login/register link:
<a href="https://cart.mindbodyonline.com/sites/[YOUR STORE ID]/client" class="btn-secondary w-full"> Login </a>
