"....THE next week..." is flagged wrong. Usage seems fine to me in English.
For me it also makes sense... both "THE next week" or perhaps "IN THE next week"...
No, both "the" and "in the" would be unnecessary in this sentence. In English, you only need to say "next week".
Though it be unnecessary, it is technically still correct!
But you could be saying something like 'in the beginning of june we're getting a new couch, then the next week we are getting a new bed'. I think 'the next week' should be accepted.
why is is not good when i put the between anyway and week