Issue: 'Failed to connect to Nextcloud - SSL handshake failed' during installation of client on MacOS Mojave

I tried to setup an user with the latest Nextcloud client on MacOS Mojave but get the error of a ‘failed connect to the Nextcloud at … - SSL handshake failed’. After selecting the option ‘SSL client certification authentication’ and selecting the certificate the installer responds with the screen ‘The side can’t provide a secure connection’.
I tried also Owncloud as a client. The installation process worked fine and got me a working client.
I also tried the web interface and also this works fine. So there is in my opinion no issue at the server side but in the installer.

I used the Nextcloud version 2.5.3 (Build 20190724) and Mojave 10.14.6.
Please can this issue be addressed so I can use the ‘real’ Nextcloud client for Mac? Thanks in advance.