By default, the platform does not have this option. You can use the following CSS code. 

Please follow the steps below:

1. Go to BuddyBoss > Theme Options

2. Under Custom Codes, enable CSS

3. Append the following:

.learndash-wrapper .ld-content-actions .ld-content-action {
margin: 0 auto;
}  

4. Save changes.

Note: Any modifications are considered as custom work already. Know more about our Support policy here: https://www.buddyboss.com/support-policy/

Screenshots

Without the code

With the code