[dabezt]

My friends... would like to install kodi 18.x into raspberry pi 4 model b with ubuntu 19.10 with ubuntu mate desktop (it runs ok!)

Team Kodi does not have PPA support for Ubuntu ARM distros for Raspberry Pi's.
If you want Kodi 18 on a RPi4, then you currently have the following options, AFAIK:
- LibreELEC 9.2.1 (Kodi 18.6)
- Raspbian Buster (Kodi 18.5 for now)
- OSMC ( (Kodi 18.x) 

Thanks for the anwser! However ... do you never suport Ubuntu for Raspbery Pi? It will be a pitty! Thnx!

[Klojum]

do you never suport Ubuntu for Raspbery Pi? It will be a pitty! Thnx!

We provide the Kodi application, and have a PPA for x86-64 Ubuntu distros.
There is simply no manpower available at this time to also fully support other Linux OS platforms.