As shown in the figure, I could not download the literature on the Android version, and an exclamation mark was displayed. Please ask what caused it. I used webdav to synchronize the literature, and the phone was Huawei HarmonyOS.
Oh, sorry, I wasn't thinking here. The Android app doesn't yet support WebDAV (and so you never even configured it in the settings). This is just trying to download files from Zotero Storage, which aren't there if you're using WebDAV.
https://s3.amazonaws.com/zotero.org/images/forums/u11361278/z6b258qwqqw6r4t40ld2.jpg
Do you think this is it?
https://s3.amazonaws.com/zotero.org/images/forums/u11361278/8hrluh452zycjsctgr9g.png