Regarding whether you can add an RF connector yourself, ask the R&D engineer, the R&D engineer's reply is: Yes, no. why?
For larger RF connectors, this can be done, although special tools are useful, some connectors require soldering, some connectors require crimping, and some connectors only require mechanically tightened nuts; however, those who do this need to follow the instructions carefully. And with some exercises and techniques, you can add your own RF connector (depending on the specific situation).
However, these hands-on possibilities only apply to larger connectors and cables. Many of the latest cables and their connectors are very thin (only a few millimeters in diameter), the connectors are fine and fragile, and any defects in the assembly can severely degrade electrical and mechanical performance. For these reasons, most cables and connectors for higher frequencies are pre-ordered from the supplier, and these suppliers need to have the appropriate equipment, tools, and know-how to terminate the specified connector to the cable.