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 Beta 1 here