On macOS when joining a WiFi network that uses a captive portal, the OS generally creates an isolated browser window to display the captive portal and allow you to enter your credentials.
Currently there's no way to access Enpass to auto-fill these credentials, forcing the user to go to Enpass in the menu bar and manually search for the captive portal information.
Similarly, when using native applications, like for example a VPN client (in my case Viscosity), there's no way to autofill the VPN credentials. Other apps, such as GPGTools attach to the right-click context menu of the password field to allow auto-filling of key material. It would be nice if Enpass could do the same, and ideally associate password entries with native applications like it currently does with web sites.