How to transfer folders to nextcloud cloud user?

Question

ownCloud/Nextcloud

Given: the Nextcloud cloud version 19 is based on its own virtual server, the data in it is stored by users of the entire company. Several Nextcloud clouds (one for each department) of version 21 were also raised on their own virtual server. You need to move from a general cloud to departmental clouds. Is there a way to transfer user files (selective) without going into the account of each of them? I raised the Rclone server, you can use it to connect a specific user container using the WebDAV protocol and transfer data, but firstly, this is long and dreary, and secondly, you need to know logins / passwords in order to feed them to Rclone. Maybe you need to use a different protocol or tool?