So if I buy the sounds using the Magix Music Maker Jam app, does that mean I have to purchase the sounds again from cstooh just to release and sell my music?
Do be aware that if you use the Soundpools it is likely that you will get hit with claims of breaking copyright or plagiarism on someone elses work which uses the same soundpools.
This is unavoidable and claims of copyright are in breach of the terms and conditions of the soundpool licences - copyright for these belongs to Magix / Catooh - you only have a licence to use them under the terms and conditions of the appropriate license - there are pdf links to the T & C of use for each of the licence types.