Installation and server related problems

Hello! I'm trying to find a way to copy my H5P content from one WordPress account to another. I use the Reuse button and download the content as an H5P file. When I upload it on my second site, I get this error. 

When I tried the same using the samples available at h5p.org, the uplaod went smoothly and I did not receive any error. 

I would really appreciate any advice as I have about 100 activities to move from one site to another.

The website says it's supposed to look like this:

hello there, fellow people. our library is very happy to use h5p for teaching purposes, but we have a little problem. please look at

https://stadtbibliothekkoeln.blog/2021/11/12/toolbox-fuer-die-facharbeit...

included is a very simple accordeon module with some text and links. nothing fancy. BUT this accordeon is invisible when viewed in a browser on a mobile phone (doesn't matter if chrome on mobile forces the desktop view, btw) and we have no clue why that is.