Migration from Nextcloud to Nextcloud Snap

Hi all,
Currently I’m running a manual installed Nextcloud environment on a RaspberryPi 3B with MariaDB. On a RaspberryPi 4B I meanwhile have installed an Ubuntu 18.04 server with the latest stable nextcloud snap. The uploaded files are stored on an external HDD. Now I need help on how to migrate my MariaDB to the snap MySql.

Thanks in Advance,
Chris