On the iPhone go to Settings/Passwords then select AutoFill Passwords and ensure that AutoFill Passwords is turned on and that Enpass is checked. Then swipe off any open applications and reopen Chrome. Enpass should then be integrated when you go to a page with a password prompt.
IOS 13.6, iPad Pro 11, Enpass 6.5.0(473), Chrome 84.0.4147.
After selecting the share icon the Enpass app no longer shows up in the list. Just missing since I updated Enpass. Shows in Safari however.