I have al 13 fixed wing certifications, owned already 3 companies and all specializations are unlocked/ticked but Cargo Transport Heavy and Charter Service VIP and yet if I try to create a Passenger Transport company it tells me that I meet 0/2 specialization requirements.
Perhaps because you didn’t purchase it before the CJ4 became available it is now expecting you to have 7.4M to purchase it instead of basing it on the cheapest aircraft.
If FS is looking at the most expensive aircraft that can be purchased, then had you purchased the Charter company when the only aircraft available to you was the Cessna then it might have only required 25K + 232K for the Cessna 172. Now that you have unlocked the CJ4, it seems to be requiring you to have 25K + 7.36M (CJ4) to purchase the Charter company.
This definitely seems to me to be a bug, and I would recommend that you report it. It should only require you to have enough to buy the cheapest aircraft at a minimum.
As an aside, when I bought the Medevac company it didn’t require me to buy an aircraft or even have enough to do so, so it doesn’t seem to be consistent for all companies.
There would be two such missions: Charter Service - VIP but also Charter Service - Private. You probably need to do Charter Service - Private first. Have you done that one?
The golden missions I see are to be flown by the 737Max, three of them 8 hours duration, marked with a star and the forth, also 737 Max, marked with a pilot cap 2h 30min. , so I don`t think they apply to my problem.