Snap install and external storage permission

[scubamuc]

How to manage external media and storage for Nextcloud snap

Managing external media and storage Snap confinement is a security feature and determines the amount of access an application has to system resources, such as files, the network, peripherals and services. Thus your Nextcloud snap is securely confined from the host system. Unless you specifically allow the Nextcloud snap to access the /media or /mnt directories on the host system, you will not be able to access any other directory outside of the confinement. External media, network shares and s…

this is well documented with an extensive wiki Nextcloud snap wiki and support and FAQ’s

feel free to ask the community, but do read the docs