PicoCMS on "hosted" Nextcloud

My Nextcloud is hosted by a provider as I have no server. PicoCMS works well, but some tweaks require access to folders outside of the Nextcloud environment. Such as change the theme of a web page, and shorten URLs. I assume I have no access to these folders. I dont know how to check.
Is there any way make such changes, e.g. Themes, from within Nextcloud?

If you don’t have access to your Nextcloud’s data directory you unfortunately can’t use custom themes with Pico CMS for Nextcloud. This is due to security reasons.

thanks. How can I tell if do have any access? I have access to the Nextcloud web interface via the URL the storage provider gave me. And the browsers address bar.

You need FTP server credentials, access to “WebFTP” or something similar.

thanks. I don’t have that access on my basic account.