Notes & Deck App issue

I have a NC system on my home dietpi server with remote access. Great cloud service!
However i have encountered some issues where i am seeking advise.
I have installed the IOS apps for Cloudnotes and Nextcloud Deck. Non of them work. I have updated the IOS to the latest. Still no luck. Any idea. Can it be that these IOS apps are simple not functioning? If yes, is there any other method to use the nextcloud notes app cross platform (PC and Ipad)? thanks