Oh right, I never solved that thing since I was so pissed off at that guy who refused to post his error, I hate those people.
Anyway, that problem was solved by this guy on centos 7 : HELP me: Email not receiveing after setting up filtering spam in rainLoop - #17 by 73Hn
Which is you have to add dovecot repo at https://repo.dovecot.org/ since the centos 7 repo has conflicting dovecot and dovecot-pigeonhole packages and you’ll never be able to install matching dovecot/pigeonhole otherwise, the two has to match, or it won’t work. My solution of just installing pigeonhole was always the solution, just you need to add the dovecot repo.
Hopefully the outsource to famous sites wasn’t too expensive!