How often do you update your media images? For example, Froxlor is on Debian 8, which I think from memory includes PHP5.
That is a question for the support (via mail / ticket). Although (sometimes) Netcup employees visit this forum, it is officially only a user-to-user forum.
Do not use one of the outdated images. Install a recent system and install your desired software by hand. Is easier and afterwards you know what is really running on your server. The images with some preconfigured stuff are heavily overrated.
If you really want froxlor, then use a minimal image (for example Debian 10) and follow the official guide (done in 2 min): https://github.com/Froxlor/Fro…Install-froxlor-on-debian