First of all: I am not a lawyer, and the following information is only my personal opinion or knowledge of how I interpret the various rights. All information without guarantee.
In general, you must observe the General Terms and Conditions of netcup itself, the law of the country in which the server is located, and the law of the country for which target groups the website was created.
According to netcup, cryptomining, for example, is prohibited. If you are concerned with advertising and the associated collection of user data, e.g. to display targeted advertising, you must comply with the GDPR (for Germany/Europe) - but in principle you are of course allowed to place advertising on your websites.
Or have I misunderstood your question?