Cannot pair Bluetooth keyboard with Vero 4K (APLIC 303324

Hi, I bought a bluetooth keyboard from ebay. I can get it working on other devices but I can get it to pair with my computer, but not with my Vero 4K.

This is the keyboard manual (in German): APLIC 303324/20180622SZ140 BEDIENUNGSANLEITUNG Pdf-Herunterladen | ManualsLib

Vero sees the device in bluetooth discovery mode. The keyboard requires a pin in order to pair but when I select “Connect with Pin” after a few seconds I get the message “Connection to Aplic-303324 failed”.

When I select “connect without pin” the keyboard works for a few seconds and then disconnects.

If anyone has any ideas for me I will be very grateful.

Thank you

Adrienne