ABPro 4.0.3 does not run under Joomla 4.
ABPro 4.0.5 runs under Joomla 4.
Features that may not come over to Joomla 4:
- Payment processors, other than PayPal.
- Email Marketing (MailChimp, AcyMailing)
Registered support customers can download the current alpha test release from the ABPro Downloads page.
See an early ABPro 4.0.5 running under Joomla 4.0 Alpha 12 here