Deckloud support,
by email, in your own words.

Write to support@deckloud.com. Say what you tried and what happened instead; a screenshot helps. If you can, attach the file from Settings → Diagnostics → Export diagnostics. It holds your app version and sync details, no passwords or board content. Never send your Nextcloud password.

• I see no boards after signing in.

  Check in a web browser that Deck shows your boards. If not, Deck may be off on your server, and whoever runs it can turn it on.

• My changes don't show up elsewhere.

  Deckloud keeps changes on the device until it reaches your server. Check that Nextcloud opens in a browser, then pull down on the board list to sync now.

• Pro from my phone on my computer.

  Pro on your phone covers both. In the desktop app, open Deckloud Pro and choose Activate purchase from phone. On your phone, open Deckloud Pro, scan the code, and tap Activate desktop.

• Deckloud doesn't work on my work device.

  Devices an employer or school manages can block apps or connections. Ask IT to allow Deckloud and your Nextcloud address.

With a GitHub account, you can report bugs or suggest features in public, where others can add what they know. Report security problems privately, by email or GitHub's private reporting, never in a public issue.